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FAQs about Crustaceans 1

Related FAQs: Crustaceans 2, Crustaceans 3, Crustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction, Micro-Crustaceans, Amphipods, Copepods, Mysids, Brine ShrimpHermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating Shrimp, Horseshoe Crabs

Related Articles: Crustaceans, Micro-Crustaceans, Amphipods, Copepods, Mysids, Isopods, Shrimps, Coral Banded Shrimp, Cleaner ShrimpP. holthuisi Pix, Mantis "Shrimp", Lobsters, Slipper Lobsters, Hermit Crabs, Squat Lobsters, Crabs, Arthropods, Pycnogonids (Sea Spiders),

Enoplometopus in a wholesaler's cubicle, Los Angeles.


Sending in the clown - flashlight trick? 7/10/04 Could not find an answer to this in the FAQ Archive.  I have an anemone crab (Neopetrolisthes ohshimai) on hold at my LFS  and I am wondering if it will be compatible with my Rose Anemone (Entacmaea quadricolor).   <it is likely to take residence here> My false Perculas have shown no interest in the anemone for 4 months now. Thanks -Ray <I have a wacky suggestion... trust me here: at night when all is dark, set up a small focused light on a timer (like a small book-reading lamp) to shine in a point on the anemone. Do this for up to 2 weeks (consistently! use the time)... and write back to tell us if the clowns went into the anemone. Many theories for why this helps... cant explain it (beyond logical theories of fishes, larvae, plankton being attracted to light). We shall see :) Anthony>

Sand Hopper ? (like Dennis?) Hello WWM crew I recently lost all my fish in my 180 gallon tank due to some disease. <hmmm... regular readers of or daily FAQs are probably tired of reading this, but... it surprises me how many aquarists are not told about or do not simply heed advice on having and using a quarantine tank to screen all new fishes... without exception... before they make it into a display. When done, wipeouts are VERY rare. Not picking on you at all my friend... but in a lifetime as an aquarist, I have seen literally dozens of marine fish that were over 10 and 20 years old in various successful aquarists tanks. 26 year old blue Regal tang, 18 year old Marine Comets, 12 year old Sweetlips (!), saw pictures of 32 year old clownfish (!!! and documented). In all cases, strict QT protocol is applied. one of the keys to success with marine aquariums. For the benefit of others reading this post, a 10 gallon aquarium, glass canopy (no light), heater, thermometer and sponge filter are well under $100... perhaps under $50 with sales or used equipment. This amount was lost many times over in a 180 tank of livestock... not to mention their lives. I trust my friend that you weren't advised to put each fish singly through a 4 week QT before entering the main display. Live rock, live sand, love food, plants, etc all the same risk of disease... all need QT> I let the tank sit for about a month with no fish to insure that the disease would go away and now after a month there are thousands of Sand Hopper's everywhere. http://www.imagequest3d.com/pages/current/pictureoftheweek/sandhopper/sandhopper.htm <indeed.. natural plankton that have flourished without fish predators. They are a great blessing! People set up fishless refugiums to keep their tanks supplied with them> Are these Sand Hopper's dangerous to fish or will the fish eat them? Any information you can provide me with would be helpful. <if they have flourished in your system for the last month and you haven't been feeding the empty tank, it is a sign of serious nutrient accumulation. Perhaps the wipeout was related to overfeeding or high DOC levels> Thanks. <keep reading and learning my friend. Do spend time in the Wet Web Media archives to help prevent the wipeout from happening again. Anthony>

Trying to identify a crustacean.  Hello. Every time I go to the Gulf of Mexico, I see these crustaceans which are about an inch and a half in length. I have heard that they are called sand fleas. However, I looked sand flea up and they are definitely not that. These animals are white to light gray or tan (at least in Destin area - I guess because the sand is white), and they burrow in the sand where the waves crash. They seem to go in backwards. They cover themselves completely except for their eyes and I think filter feeding mouth parts. Their carapace is oval (They kind of look like a giant white peanut M&M.) The filter feeding mouth parts (which are two per animal) make an indention in the sand when the water goes back out. Anyway, I really have wanted to know their name for quite some time. I hope this is making sense.  Thank you for your time. Carolyn <I have known them by the same name of "Sand Flea". There are more than few species and genera this applies to. If you'd like the scientific name, we can consult an Audubon field guide or perhaps find a nice online coastal ID website. Kindly, Anthony>

Brittle Star, freshwater/marine algae, euryhaline sea minkees Hi, Bob and experts, <<And hello to you...>> I just brought two brittle stars and I would like to know whether is it safe to keep in a DSB? One is a Banded Serpent Star (Ophiolepis superba) and one is normal brittle star (Ophiocoma sp). Both are about 3-4 inch big.  <<As long as they aren't green brittle stars [these can be predatory] you should be all set. These seastars really don't do much below the surface of the sandbed.>> 2. Just curious to know whether a fresh water algae (seaweed) is able to grow in salt water? <<No, I don't think so... different osmotic balance required in cell walls, etc.>> 3. One last thing, I planning to keep brine shrimp. Wonder I will stay alive in saltwater? <<You mean like Sea Monkeys? No, they need true brine.>>  and if yes, can I add those stuff into my reef tank after it hatched?  <<You could add it like food, but I wouldn't add these as inhabitants. The resulting die-off could spell disaster.>> Thanks. Regards, Danny <<Cheers, J -- >>

Teeny Tiny Somethins' Hey Bob and Crew! I am so thankful that you super fish guys are out here, I don't know what I'd do otherwise. I have learned so much here, actually, just enough to realize how much I don't know! I do apologize for the length here, I figured it was best if you had more info than not enough. <Yes, we can always sort through what we don't need, but cannot be helpful if we don't have all the information.> I've searched EVERYWHERE, and can not seem to find an answer, alas here I am. I'm sure I'll blush with embarrassment when you give the kindergarten level answer as well, so go easy on me. <I will try.> I am new in the saltwater world, duh, and I am wondering what the little organisms are that are cruising all over the bottom 1/4 of the tank. They are clear and have two little antennas, a head and another section that's a little longer than the head and then a tail like kinda thing. How's that for a vague description? <Good enough, sounds like a amphipod. Type this term into the Google search engine on www.WetWebMedia.com and I am sure it will direct you to more information and a link to pictures.> In a way they kinda remind me of a teeny-tiny brine shrimp. These guys are small, I need to use a photographer's loop to see them. The 55 gallon tank has been up for about 6 weeks, and has cycled. I have 2 penguin 330 bio-wheels, and one HOT Magnum canister filter that does have charcoal in it, (saving for a protein skimmer) a Rio 600 to just create some current, one good size piece of live rock (about 8 lbs.) that has some green bubble algae and some green hairy tufts that the hermit crabs haven't chowed on yet. Oh, and some small clam that was a hitchhiker on it. I have about an inch or two of live sand, and crushed coral sprinkled heavily on top. I am low on $$ from the initial set-up, so I'm forced to take this slow. The only livestock I have are, a Yellow Watchman Goby, and a Green Serpent Star. Which by the way NEVER ate a fish ever, <Yet> and even the Goby likes to hang out with her! So I was mortified when I found out, from reading your info of course, that they are trouble. <Perhaps not. Have you seen a picture of the fish eater?> I was actually going to email you back then toting my Star's humble behavior, when I noticed my damsel was MIA. And since the star looked extra healthy.... well you know the rest. :^( ah, another statistic. <I understand.> Okay, so now that I completely got away from the subject at hand, I'll leave you alone now. I so appreciate any help and info that you can direct my way. Thank you so much for your time, and I'll keep on plowin' through the data! Sincerely, Dee <Have a nice day! -Steven Pro>

Copepods Hi, I don't have any live rock in my tank, so where could these of come from? <in the water carried with fishes on import, on a fish, from the sand, etc> I feed the fish freeze dried plankton and frozen krill. This little organisms seem to be increasing in number? are they beneficial?  <the organisms are good but significant increases in population either mean that you have no natural fish predators on them (unlikely) or there is some overfeeding of the tank, or the skimmer has not been performing daily, etc> I have had the puffer for about 2 months now and seems to turn blotchy when he surfaces the water and goes by the powerhead. he makes a splashing sound then turns blotchy. he is the only fish in my tank to be giving me a problem?  <sometimes the color change is from aggression, posturing or a fright pattern... not always bad> all the others are fine and eating well. thanks, JPK <very welcome. Anthony Calfo>

Strange Things in Filter I just cleaned out my filters in my overflows - the spongy things. Anyhow, when I was taking them to the sink, I noticed all sorts of little things moving on them and jumping onto my hand. They kind of looked like clear brown brine shrimp or something. I imagine they were feasting on the 'stuff' that the filters catch over time. Anyhow, any idea what they are? <Sounds like amphipods> Are they good or bad to have in your system ? <Good> Jim

Clicking Crustacean Hi <Hello> First I want to say your site is a wealth of information, and great even for a new comer to marine keeping like myself - many thanks. <quite welcome... please pass along a good word to other aquarists/dealers> Recently I have set up my first reef aquarium - 150ltr. I added my live rock 10 days ago, and though told it was cured, seem to be now going through a curing phase <very common... almost standard (the lie by mail order vendors of "cured" live rock> with ammonia off the scale, as yet no nitrite. How long will it usually take to cycle past the nitrite phase?  <2 weeks... less with aggressive skimming and very strong water movement> I removed the dead organisms, <excellent> added live bacteria,  <a waste of money... actually added to rotting dissolved organics. Very dubious products> changed water and there doesn't seem a lot of waste matter.  <very good!> Will the coralline algae and red sponges survive? <coralline likely yes... sponge... perhaps not> Secondly, I appear to have gained a stowaway, which has made a home (burrow) in one of the brain corals previously attached to the live rock (now removed and in ammonia/nitrite free tank). It is a small shrimp that seems to be nocturnal. I hear it more than see it. It makes a clicking noise similar to glass splintering, and can be hear across the small room the tank is in. What is it and is it likely to be a problem in the coral reef tank I am setting up? <likely a mantis or pistol shrimp... neither harm coral much or at all... both can be a minor nuisance to small fishes. Mantis a perhaps a little worse. Do review archives for pictures to help with ID or trapping techniques> Many thanks Brett Moloney <best regards, Anthony>

Ich Question Hello, Is it possible to see free swimming Ich with the human eye? <I do not think so. Some of the adult parasites are visible on fish. They are anywhere from 60 to 370 microns in size, but the tomites (free-swimming stage) are much smaller, 25 to 60 microns.> The reason I ask is because my tank is infested with little white parasites I can see swimming in the water. The 125 gallon tank currently houses 80 pounds of live rock, one medium yellow tang, a cleaner shrimp, and a few snails. I am currently deploying a quarantine tank, which I should have had initially. <Agreed> How do I rid of all these parasites? <Not sure you have parasites. Are you fish showing signs of distress? These could be harmless/beneficial plankton or a larval stage of some other liverock hitchhiker or even air bubbles.> I know I cannot run copper with live rock. I am currently using Kick Ich. Have you heard about this product? <Yes> Is it any good? <It has mixed results, but I always try to avoid using any medication in the main, display tank. Too many other unintended consequences.> Please assist. Thank you. Peter <Please read through the archives on fish disease and familiarize yourself with the symptoms. From your description, I do not believe you have any parasites. -Steven Pro>

Ich Question II I know they are not air bubbles. I can see them crawling on the glass of the aquarium, so I know they are parasites/bugs of some sort. Do you really believe these are beneficial? <Yes, sound very much like Amphipods or Copepods.> I really need to discover what these are. I know I had Ich up until last week, but if you say that the human eye cannot see Ich, <Cannot see the free-swimming stage/tomite.> what can this possibly be? Please assist. Thank you. Peter <See if you cannot find a picture of your creatures at one of these websites; http://www.tcnj.edu/~maughme2/faq.htm or http://www.rshimek.com/animal_identifications1.htm -Steven Pro>

RE: Ich Question I know they are not air bubbles. I can see them crawling on the glass of the aquarium, so I know they are parasites/bugs of some sort. Do you really believe these are beneficial?  <Much more likely innocuous, beneficial than harmful> I really need to discover what these are. I know I had Ich up until last week, but if you say that the human eye cannot see Ich, what can this possibly be?  <All sorts of possibilities... worms of a few phyla, many crustaceans, meiofauna... Look to sources of food, unfilled niches, just time going by and "good maintenance" re these wee beasties... take a read here: http://www.wetwebmedia.com/invertfa.htm and maybe look into looking into a microscope... Bob Fenner> Please assist. Thank you. Peter

Live Rock  Hi, I am new to marines and was wondering if you know what the small about 2-4mm whitish things with many legs are that I see at night in the gravel and on the live rock Thanks Tim  P.S. excellent web site <Thank you, please read it here: http://www.wetwebmedia.com/invertfa.htm Bob Fenner>

Bugs and Bubbles! Robert, Anthony, Steven... now that I have read all of your accomplishments on "Wet Web Media Crew", I must say I am a bit intimidated  <don't be... we got drunk and made all of that stuff up in our bios... laughed our butts off the entire time> to say, "what are those little bugs in my sand." OR " I recently read about the dangers of "little bubbles", and now I am paranoid when my air stone ventures too close to my powerhead and spews out zillions of minute bubbles!" <Ahhh... really no worries at all. All easily corrected.> I would love to have just ONE of Fenner's degrees, ahhhhhh. <I spoke to him... he said you can have his degree in Basket weaving... but no-one is touching his Badminton Masters> So, with that said, be gentle with me! The bubbles and the bugs. The former have 8 legs, 4 mouth parts a forked tail, 2 antennae, and a barely visible with the naked eye, so I used a loop! Actually, they look like roaches, ugh! <yes... these and many more in the following useful links: http://www.reefs.org/hhfaq/pages/main_pages/faq_rock3.htm and http://www.rshimek.com/odd_critters.htm> Pam, Thank you~~~! <with kind regards, Anthony Calfo>

Copepods & Amphipods Just wanted to start off by saying that I'm new to the hobby and your site is an incredible resource for helping me along. <outstanding...keep learning and sharing> My 15-gallon setup is 6 weeks old and I've got two questions: 1) My red open brain has been in the aquarium for 12 days now. I have observed him swell about 2 hours before the lights come on in the morning, but no sign of his tentacles coming out. I've tried spiking the water with juice from frozen brine shrimp, Mysis shrimp, and clam. No dice there, either. He's sitting on the sand bed.  <all good and appropriate... nice job on the homework <wink>> Water parameters seem to be OK (NO3 <0.2 ppm, dKH=10.2, sp. gravity = 1.021, temp = 78F, 55W PC Lighting 50/50).  <in the long run, do keep the salinity "higher" (closer to natural 1.024-1.026) for invertebrates. Lower salinity is recommended for fish only> Is there anything I'm doing obviously wrong?  <nothing stands out as even moderately inappropriate. The red open brains are deeper water and if the acclimation period was not very gradual, the coral may be disturbed for this reason. See the following for insight: http://www.wetwebmedia.com/acclimcoralslight.htm  Still... the inflation is usually part of a feeding strategy. Perhaps the Trachyphyllia was getting some sustenance after all?> 2) I've recently been reading about detritivore/fauna kits that are beneficial to add to a reef aquarium (i.e. those available from Inland Aquatics).  <yes... very nice!> Supposedly mixtures of Gammarus, Mysid shrimp, micro stars, chiton, and bristleworms. Are any of these worth adding?  <all to some extent can be beneficial> I currently only have cleaner shrimp, peppermint shrimp, the open brain, emerald crab, turbo snails and scarlet hermits. My sandbed is 20 lb aragonite + 3 lb live sand from my LFS. (Also have 20 lb live rock). Thanks, Greg <fresh live rock, live sand and microfauna are quite desirable to add periodically to freshen up the tank/diversity. Go for it! Anthony>

Dying Crustaceans Hello again!! We're having a little problem . .. Here are our tank specs: 90 gal all glass aquar. Berlin Sump protein skimmer 3 total powerheads Parameters: pH: 8.2-8.4 Spec Grav: 1.023-1.024 Ammonia: .25-.50 <Should be zero.> Nitrate: 0 Nitrite:  Our tank has been set up for one month. We cycled it with 100 lbs Fiji live rock. One week ago we put 2 Percula clowns in (which are doing great, eating, swimming, color is good), 13 turbo snails, one black spiny urchin, one red legged crab and one blue. Everyone was doing fine until on Wednesday (we added everyone on Saturday) we noticed a dead snail in the morning and then one this afternoon. The LFS told us that was fine and gave us 3 more turbo snails and 2 sally light foots. Then we kept noticing about a snail death a day. Crabs all doing fine. Again, the LFS (which is a great one by the way) said everything was fine. Then this morning we noticed one of the sally light foots and a few more of the snails were dead. We were a little distressed. Keep in mind, fish doing fantastic!! We called the LFS and they said it could be copper b/c we used distilled water initially and have been topping up the water with distilled. <Possible, I do not like/recommend distilled water for the same reason, metal contamination (copper, iron, aluminum, etc).> But I did some research on this and it says that the algae would be greatly affected by copper too and we have a massive overgrowth of hair algae and tons of other macro (grape, etc) algae growing in our tank. <Copper and iron are both nutrients to algae and plants and would promote their growth.> We're going right now to the LFS to get the water checked for copper . . . but we're a little discouraged. Do you have any input for us?? <Wait for the test and see what it says. Also, put a Polyfilter in the tank somewhere and see what color it changes to.> Thanks for your time!! Katie <You are welcome. -Steven Pro>

Dying Crustaceans II Hello again, Thanks for the advice. We went to the LFS and had our water tested for copper and it was totally negative. So we didn't buy the filter. <The Polyfilter would give you an idea if it was something other than copper, another contaminant.> They chalked it up to a bad batch of snails. They had many dead ones in their tanks. <Perhaps, they do not tolerate changing salinity well at all.> So we weren't worried about it and bought a red lipped blenny yesterday. He's doing fabulously, going crazy pecking off the live rock. Looks great. But a new problem this am. One of the clowns has a bulging eye. I'm assuming it's some sort of infection. <Probably a slight physical injury with a secondary infection causing a buildup of fluid behind the eye and bulging/cloudy. Try one tablespoon of Epsom salt per five gallons of water in the main tank. This will help relieve the fluid and allow the fish's immune system to kick the infection. You can also feed a medicated food for bacterial infections.> We'll call the LFS today for info on treating him, but we're so distressed!! We're doing a 10 gal water change today to hopefully pull the ammonia down to zero and we're washing all the sponges (in the overflow and sump) and changing the carbon out. Anything else you can recommend?? <See above. My first instinct is to test water and then do a water change whenever anything is amiss.> Thanks again. Katie <You are welcome. -Steven Pro>

The Mystery of the Missing Arthropods WWM dudes.... Been reading the daily for months and thanks to the advice/errors of others have never before felt a need to write myself. Getting business out of the way, I have a 29 gal glass w/2/24"VHO, Remora skimmer, 45lbs LR, 40 lbs LS, params as follows: Salinity 1.027 Temperature 78-80 pH 8.4 Alkalinity 8.4 Calcium 460 Ammonia 0 Nitrite 0 Nitrate 0-10 Daily dose of Kent Liquid Ca, Iodine, Super Buffer dKH Livestock: 2 small damsels, 1 maroon clown, 1 E. quad BTA, 1 Colt Coral (Alcyonium I believe), 2 Peppermint shrimp, 1 Emerald Mithrax crab, 1 Serpent star, 7 Hermit crabs, 4 Snails My issue: Two weeks ago on of my peppermint shrimp molted (as evidenced by an empty carapace) and disappeared, never to re-surface. I was expecting that had it been murdered there would have been some evidence of the crime, however there was none, nor an expected spike/rise in ammonia levels. As I have a small tank, every critter in it tends to be visible, so the antics of the missing shrimp were sorely missed, I replaced him on Friday. Yesterday (Sunday), I was checking things out when I noticed that my Nimble Crab (Sally Lightfoot) was in the process of molting. I called that entire family down to watch for a while (all were suitably impressed), but we eventually wandered off (attention span issues I think). About 15 min later I stopped back just in time to see my Mithrax Crab ripping the Nimble into bite size bits, (didn't call the family down for this one), eventually the serpent star wandered over and abducted the corpse in one fell swoop. Alas, I think the mystery of the missing shrimp has been solved at the expense of yet another poor critter. To my query: When purchased, the Mithrax was supposed to be a herbivore, and does a good job at cleaning the algae off my rock. However, the attacking and eating of the molted crusties implies otherwise, and leaves me wondering if I have too many cleaners and not enough to clean. <No, these guys are in fact opportunistic omnivores, that will eat anything that they come upon and can consume. Their claim to fame is that they are one of the few creatures to eat bubble algae.> Will I need to begin supplemental feedings for the crabs, shrimp, and starfish, or offering some change/variety of foods for them, or is there just a balance that will be reached and settle out after time? <Not a bad idea to supplement their feeding with prepared foods in a 29, but not a guarantee that your crab will not decide to consume one of his tankmates in the future.> Thank you for your time, keep up the good work. Lou G <You are welcome. -Steven Pro>

Small white/translucent parasites? Hello! I've been trying to identify these small (2-4mm in length) translucent, white bugs that are crawling around on my live rock. At first I only saw them on the live rock, but now I'm noticing them on regular rock, on the sand, on the glass, etc. They have 2 antennae, 8 legs, and 2 "butt antennae". The seem to only walk by waving their legs in an undulating fashion, never seen them swimming or burrowing, and they move in spurts of motion. I'm worried they could be fish lice or something like that, but I can't find a good photo of fish lice. They fish all seem to be okay - no weird behavior changes in the past 3 months, no lumps or spots, visually okay. I've tried to identify them using the Marine Hitchhiker ID FAQ (http://www.reefs.org/hhfaq/index.html), but there were no pictures or descriptions quite like the ones I saw. Any ideas? I can't seem to get a photo of them b/c they are very tiny. Thanks for any help! Your site is a wonderful resource! ---Stella <Take a look on the Net, books under the term Amphipod. This large group likely contains what you see. Bob Fenner>

Pistol Shrimp & Lobster (Crustacean Battle Royal) I have a 65gallon tank w/ lots of live rock and plenty of hiding spaces. Along w/ my fish, I have a scarlet cleaner shrimp, a coral banded shrimp, a pistol shrimp and a purple lobster. <things sounded great until you hit the lobster> The purple lobster was the last addition and I have noticed that the pistol shrimp pays him much attention.  <pistols are indeed territorial> The lobster has found a nice hole and rarely comes out. I know he is nocturnal and also very shy by nature, but is he scared for his life! <largely natural reclusive behavior> Will the pistol shrimp attack him? They are approx the same size. Thanks AA <a pistol shrimp attack is the least of your problems...hehe. If the lobster lives long enough to see adulthood, it will catch and kill anything it can get its hands on. A great stress to many fishes trying to sleep at night and the cleaner shrimp will be the first crustacean to go as it is weakly defensive. The lobster is going to be a tough cookie down the road. In the meantime...yes, I suppose the pistol may harass him. Do make arrangements for other quarters for the lobster. best regards, Anthony>

Re: Pistol Shrimp and Lobster II Thanks for the reply, a couple more quick questions if you will. I thought a purple lobster was very docile, even considered reef safe?? How large is he going to get? I thought 4inches. <they are indeed less aggressive than others... but they have formidable claws nonetheless and for a reason. Form follows function... and so, it may only catch and kill 10% of what the worst lobster can, but a kill is a kill. They are predatory omnivores... not vegan...hehe> Lobster aside, will the pistol shrimp attack the other shrimp? <pistols are pretty feisty and territorial. You don't want to make a habit of collecting many/other bottom dwellers to threaten him/her.>

Little Critters Hey Guys... <Steven Pro this morning.> You really helped out last time I e-mailed about fish selection and my mix...thanks again. <You are welcome.> New question...I am new to the hobby and this is a paranoia query. I have been curing my live rock in tank for a couple of weeks now and a new organism has appeared. They (five to six in number) are little bug/shrimp like looking fellows about 1/8 inches in length. They are transparent, multi-legged and have two wispy antennae at the front and a shrimp-like fin toward the rear. The seem to be meandering around the more vegetated areas of the rock. Please tell me these aren't the babies of the dreaded Mantis Shrimp I've been reading about. I searched your site but only found one image of a Mantis larva and mine don't seem to have the big googly eyes of the pic. Any idea as to what they might be? If they are detrimental how do you get rid of them etc... Thanks again and I look forward to hearing from you. <They sound like amphipods or maybe Mysis. Do they have an arched back? Then they are amphipods. The description of a "shrimp-like fin toward the rear" makes me think you may have something else, Mysis. Not harmful either way. We really need to get some macro photos of these various critters. -Steven Pro> Dave: Aspen, CO

Missing Perc I recently purchased 2 clowns for my 30 gal. reef tank. The next morning, one of the clowns had disappeared. There was not a trace of it in or out of the tank. However, I do have a pistol shrimp (not a mantis). Could the shrimp be guilty of this crime? Have you ever heard of this happening?  Since I have your attention, I might as well ask you another question. I purchased a Jawfish the same day as those Percs. A few days after the Jawfish found a nice little "home", the pistol shrimp extended his burrow to include the jawfish's tunnel. Now the Jawfish is probably stressed because I have a territorial pistol shrimp. Any suggestions? Is there a chance that the pistol will pick on the Jawfish or any clowns for that matter? Are my shrimps, crabs & stars lives in jeopardy? I thought pistols were reef safe. <No reef animal is completely "reef safe", as they all live there and must eat something that occurs on the reef. I have a pair of pistol shrimp which have killed a Purple Pseudochromis, Blue Damsel, and a pair of Cleaner Shrimp. They were all new fish except the Pseudochromis and strayed too close to the shrimps' home. The Pseudochromis went over there while I was cleaning and snap-snap-snap, never came back out. Pistol shrimp are capable of killing, but it is an unmistakable, very loud attack. They are also quite capable of scavenging a fish that died from other causes. Keep an eye and an ear out for your shrimp's attack. I like my shrimp a lot, but when they get moved to the new tank, they are going in the refugium by themselves.> Thank you, AJ <You are welcome. -Steven Pro>

Bugs? Good Morning -- Happy Monday! <Cheers, Anthony Calfo in your service> You've been a great help the past two times, so "they say" to always bet the trend. So you're the trend! Anyway, I'm new. 25 gal reef tank -- all the essentials. Aquarium looks great after 5 full days of installation. Algae growth is coming along GREAT -- temp and spg are all in check. Apparently my live rock has brought along some surprises! I've got some nice snails and there is even a few but extremely small "coral-looking" green [things] that open and close. They look like the top of the feather duster but are bright green. My question, though, is what are the "bug-like" creatures that I see running around my sand. They are so small, only the size of pen tip or a bit larger ... and they usually scamper under the rocks when the lights come on (or go right down into the sand). I can't find any information on what they are and they are so interesting to watch. Any ideas?  <yes...most likely copepods (dots like fleas) or amphipods (a bit larger and arched backs like micro-shrimp)...natural plankton. Best to allow the population to grow as large as possible before fish are added. A sign of good quality live rock/sand> Thanks a ton!!! Ari Klein <best regards, Anthony Calfo>

Crustacean nutritional value,  Foods Is Mysis shrimp any better in nutritional value ? <Yes, they are considerably better than Brine Shrimp.> I'm having a bastard of a time trying to get him to take Ocean Nutrition flake. I think I might try and get him Ocean Nutrition Prime Reef frozen pellets which I hear are good. Some have recommended Mysis shrimp, and that's why I ask. Even chopped up fresh shrimp isn't enticing the cow. . . -Ed <You might want to try mixing the Brine Shrimp and the Mysis at first and slowly cut back the amount of Brine. Frozen clams and bloodworms are also favorites of mine, as well as, all of the frozen Formula foods from Ocean Nutrition. -Steven Pro>

Amphipods ID just found your site and I like it a lot. I think I have a big problem. I have a 90 gallon salt with gravel bottom, 10months old. 4 mo. ago I noticed 1 type of bug living in the gravel they are 1/64 -3/8inch long they appear to be clear with a black stripe thru them and have long tentacles and seem to have a lot of feet, they are U shaped most of the time. at 1 am last night I turned on the hood lights and they were everywhere in the tank (over 1500 that I seen) I bought 20 pounds of live sand 5 mo ago and think that is where the problem started. I have a scooter blenny who tries real hard to catch them but he is fighting a loosing battle. I talked to a couple fish stores about it and got little to no help. the tank floor is 3/4 gravel with filter then a Plexi divider with the last 1/4 live sand-sand mix .I do not want to tear the tank down and start over so please help!!!!! thank you very much for your help if possible) frank. <No need to worry, Frank. These sound like they are merely amphipods and are beneficial detritivores. Your scooter blenny is very happy you have them as a natural food source. -Steven Pro>

Shellfish Dear Mr. Fennel, We are trying to find out why blue crabs and lobsters turn red when they are steamed for a science project. Where can we find out about this? Thanks, Kerry and Brenden <Interesting. Please see here: http://www.wetwebmedia.com/litsrchart.htm re how to do computer searches for such information. "Get thee to a large college library", Bob Fenner> P.S. We need to know by Mon.1/22/02. Thanks.

Crabs Hi Robert I have recently been hearing a cracking noise which I thought was a mantis shrimp but I discovered a crab that seems to be making the noise can crabs make this noise or is it most likely a mantis shrimp? <The ocean realms are indeed noisy places... there are crabs that make significant noise, though most often in aquariums it's Alpheid Shrimps (Pistol), and stomatopods that are to blame as far as crustaceans go... Bob Fenner> thanks for your help

Something in my aquarium Hello... I have a fish only saltwater aquarium with live rock. I currently only have a clownfish in there as to start. This morning I noticed a lot of white things crawling and chasing each other on my tank walls, they are small... but I can make out a tail, they are not swimming, just crawling on the walls. Can you please tell me what these are, and are they bad, if so. how do I get rid of them? <No problem. Please see here: http://www.wetwebmedia.com/crustfaq.htm Bob Fenner> I know they are not brine shrimp...that I do know. Your help would be appreciated. Thanks, Jason

Any non-fish for a community tank? Mr. Fenner: Thank you for your prompt reply and helpful information in response to my questions about freshwater lobsters and crayfish. <You're welcome> (My interest in these crustaceans and the like is purely non-gastrological, though) <oh> If lobsters and crayfish are not ideal candidates for a community tank... are there any invertebrates that are? Any that won't be eaten by the fish? <Yes... depending on which species we're talking about... of a certainty there are ones that can/do/will eat each other> Must have fish and invertebrates (and not eat them) too! Please help! AHR <Do take a read through the various fresh and brackish water sections (livestock sub-sections) posted on WetWebMedia.com for input on selection, choices. Bob Fenner>

Lobsters in Galveston? Hello Dr. Fenner, I have written you before about my excursions to the muddy and murky waters of Galveston Bay. <Yes, I recall> Today, while catching ghost shrimp under the causeway (for my very hungry flounders & sea robins) I happened upon 2 critters that look a whole lot like lobsters and not crayfish. The largest one (the other is too small to tell), about 11/2", is greenish gray with bands all down his tail and one very large claw & one small pincher. It also has 2 sets of antennae (whatever they are called), 2 out to the sides and 2 in front. After just a short while in my tank this crustacean started moving pebbles around to build a shelter. From what I could read, it looks to be a lobster, but a friend of mine insists that they can't live in Galveston. Who wins this bet? <Mmm, well, there are lobsters known from the area... but don't think this is one of them. A large claw (you should only have spiny lobsters, palinurids, there... but there are snapping shrimps (Alpheids), other crustaceans that fit the bill/description. Bob Fenner> Thank you for your time. sincerely, Steve Tilotta

Re: lobsters in Galveston? Once again I lost a bet, but gained some knowledge. Indeed you were correct, it is a snapping shrimp. I was surprised to see that they sell for $18 on one site. <What's next? Folks paying big bongo bucks for fleas, ticks, cockroaches?> Maybe I can make a few trades with the pet stores I frequent. Thank you again Robert for your assistance. Steve <You're welcome my friend. Be chatting. Bob Fenner>

Refugium bugs?? Hi Mr. Fenner, How are your holidays going? <Fine... to me all days are... holidays> I have a question concerning the little critters in my refugium. I've been doing a lot of searching on the internet to i.d. a certain critter in my refugium. The closest thing I have found was a couple of drawings on a few different sites that resemble what I have. They are drawings of a Gammarus shrimp. Being drawings it is hard to say exactly that is what they are. <Mmm, not to be seen as being disagreeable, but all imagery is "drawings"... moving ones... one "drawing" after, before another.> The thing is all the sites mention they are freshwater while my tank setup is a reef SW tank. Are there also SW species of Gammarus? <Mmm, likely other species of crustaceans here... copepods, amphipods, mysids...> Mine are greyish colored with their backs curved under, and short antennae like things from the end. They have long antennas, and it seems like their legs are towards the back only with some little appendages towards the front, and I do notice 2 bigger appendages in the front that looks as if they are tucking them under their chest area. These guys are very fast when they walk around, and never have I seen them swim. When they are running around and they turn they tilt to the side like a speed bike taking a curve if you know what I mean. I have not seen them going after any other live thingies in the refugium, except they seem to be picking off the ground, and are often seen climbing around on all the Caulerpa growing in there. I think they are eating up the dead, or decaying parts of the Macroalgae that there is because I watch them and they do not eat any of the good, and growing Caulerpa. Am I right in assuming they are Gammarus, and are they o.k. to be in a refugium with Miracle Mud, and Caulerpa hooked up to my reef tank <Take a look through the "Links Pages" on WetWebMedia.com to find the link to the "Critter id" part of the Net... and consider a small microscope like Intel/Mattel's QX3... a great tool. Bob Fenner>

Feeding behavior of barnacles Hello Mr. Fenner, My name is Jacob Valdez. My seven grade science project is about the effect of environmental changes on the feeding behavior of barnacles. In general, how frequent should I feed barnacles or other marine invertebrates with brine shrimp? <In general... Mmm, not all marine invertebrates, including Cirripedians actually feed or will feed on brine shrimp... But, the feeding of these crustaceans to other animals involves the usual admonitions to do it "carefully"... in small amounts, observing that they're actually being taken... on a regular regimen, more frequently rather than less (a few times a day, or throughout the ingesting diurnal rhythm of the barnacle species in question> In general, what are the range of temperature, pH level, salinity, lighting, and the amount of brine shrimp for the barnacles?  <Too general a question... What species of Barnacle are you utilizing?> What happen when we over fed barnacles or when there are excess food? <A mess... pollution levels rise in their system... at its worse, poisoning, biological collapse> Do barnacles eat when it is dark?  <Some species do... has much more to do with tides, training> Do barnacles or other marine invertebrates eat only eat during daylight? How do they sense food? <Chemical and touch...> I hope you will respond to some of the above questions. Have a Merry Christmas! Jacob Valdez <Have you had occasion to visit a large public (better college/university) library? Please read here: http://www.wetwebmedia.com/litsrchart.htm re information searches. Bob Fenner>

Mantis Shrimp/Blue Lobster Do you think a Mantis Shrimp would work out in a tank with a Red Volitans Lion, Spiny Puffer, and Sargassum Fish? Thanks, I was just trying to think of a crustacean they wouldn't eat. Would a Blue Spiny Lobster work too? Thanks <Both risky propositions come molting time around the Puffer. Bob Fenner>

Re: Unknown organism Hello,  I have extremely tiny white flea-like organisms crawling on the inside of  my tank when the lights turn off. There are hundreds of them milling  around. They appear to be from top to bottom. I have tried searches to  find any info on the matter with no luck. Is this something you have heard  of and should I be concerned?  <Likely some sort of crustacean... amphipods, copepods (an easy guess... thousands of species). Nothing to worry about... more helpful than  harmful... cleaner uppers, food sources... They too shall pass. Bob Fenner>  Thank you for any help, Tony 

What are these creatures? Dear Bob, I have been reading lots of FAQ's on your web and I enjoy it very much. I guess now it's my turn (just like everybody else) to ask for your help unfortunately. <Not unfortunate my friend> I have a 75 g fish only tank. I have a purple tang, 1 yellow tang, 1 tomato clown, 3 damsels, 1 Humu Humu trigger and 1 lemon peel angel. Chemical levels are perfect (except nitrate: about 30), temp is 79, 20 lbs or live rock. Almost a month ago, when I was cleaning the 350 magnum external filter and replacing the carbon after I treated the tank with copper for ich, I found some little creatures in the water in the filter (only in the filter at that time). This morning, in a sudden I found these little creatures again, this time they are in the water in the tank. They are about the size of the tiny, tiny, smallest possible bubbles, and same color. The only way to distinguish between these creatures and the bubbles is that these animals are moving. The fish haven't shown any signs and symptoms yet. However, I really need to know what they are and how to get rid of them. I am afraid they are going to take over the tank soon. I appreciate your help very much and you have a nice holiday. Quang. <Very likely a small crustacean species (perhaps a copepod of some sort/s)... and very likely no problem... I would not make extraordinary effort to remove them. They are probably much more beneficial (clean up, food) than harmful, annoying.... and will "pass" on their own in time. Bob Fenner> Sand "Fleas" Hey Bob, Years ago I would surf fish in Florida with my Family. We always used "sand fleas" for bait. I noticed that they loved to dive into the sand, and did not get all that big. Do you know if they could be used in my live sand substrate to stir it up? Do you know if there are any problems with them? As always, thanks for you response and great advice. Kevin <Likely some sort of Sand or Mole Crab, like here: http://www.assateague.com/mole-cr.html Not easy to keep in captivity, due to life history, being covered, uncovered by tides, waves... but worth investigating for sure. Bob Fenner>

Isopods - I loved them as a kid Hi Bob Fenner, Ah,... the days of collecting rolly pollies in a jar and playing with them for hours are long gone. Now I spend my days chasing after them in my tank with a rigid airline tubing waiting to either suck them up or smash them to death. <Yikes!> My tank has been fallow for almost a month now and the invertebrates are taking over! I have now noticed isopods in my tank and having been managing to catch and dispose of several of them. Are all isopods found in a marine environment parasitic to fish? <No... and these may not be isopods...> (no, Jana they aren't - that's my guess). And how do I know if the ones I am finding are keepers or creepers to get rid of? <Do you have a pic? Are all their legs about the same size, make-up? Are any of them swimming, hopping about, or all just walking?> Have a good day, Bob Fenner. You are a winner! (I'm feeling very poetic today) <Ah! A good day. Bob Fenner> Jana

RE: isopods - I loved them as a kid May not all be isopods, huh? Ok. That's good to know. What else looks like an isopod, but isn't? Here is a little better description of them: They are solid white, except for their tiny little black eyes. They look much like my childhood rolly-pollies as far as their body structure is concerned. They are anywhere from 1-5 mm long (rough guess here), and I have seen them swimming and walking. And all of their legs look like they are the same size (isopod = all about the same legs,...see, I do remember some stuff from Biology classes). I do not have a microscope (kind of wish I had and old school 100X one,... would be fun to put some of these critters under and get a good look), so I am not sure if all of their legs are the same, but as far as I can see they look like they are the same. Thanks for the help, Bob Fenner the Winner! Jana <Mmm, likely some sort of amphipod or even copepod... put these names in your search engines and take a look... And, by the way, there is a real neat (up to 200X) microscope that Intel and Mattel make that hooks up to your computer... real fun and useful... can "take pictures", even kinetic, send on the net... Take a look: http://www.intelplay.com/products/qx3/ for $99 US... a very nice gift as well...Bob Fenner>

Isopods I have a 95 gallon marine tank that I am maintaining for an invertebrate zoology class here at Penn. St. I recently developed a large population of small (3-8 mm) isopods in the tank. They are in the process of eating all of the algae in the tank, which is the food supply for my gastropods, nudibranchs, and sea urchins. I was wondering if there was something that I could add to the tank that would eat the isopods. Unfortunately, I am constrained by the fact that I can't put any fish in this "invert-only" tank. Any ideas? <Yes... a small/er species of Stomatopod... Mantis Shrimp should do it. Bob Fenner> Erik E. Cordes Biology Department Penn State University

Tater Bug in my tank!  I had my light of and when I turned it on I saw a potato bug creature swimming around then he went under the sand any idea what it might be thanks. <A potato bug? Rollie-Pollie? Sounds like an Isopod crustacean. Put the word "isopod" (or amphipod maybe) in your computer search engine... Bob Fenner>

Mystery crustacean/s Hey Bob, I read that you were at AquaTropics in Clifton NJ  <Yes, nice folks. Hope to be visiting thereabouts this coming December while out east> about a month ago at a big sale they were having... I was there too, wish I would have known you were there, would have liked to have met you... anyway, I have a successful reef tank, but I night, when I get home late, and the lights have been off for a few hours, I've noticed some unexpected guests...they seem to be tiny shrimp-like creatures that run around on the glass in group (there are a lot of them, like 20 or more). they are like 1/4 inch big, some smaller (like the size of a pin-head), and seem to be in a curved "C" like shape. any idea what they might be??? <Yes... one of many possible species of crustaceans... very likely beneficial... cleaning up, providing food...> I don't think they are doing any damage to the coral, I guess I'm just really wondering what they are and how they got in my tank. <From foods, other livestock, substrates... do check out the WetWebMedia.com invert. pages, and the link to a resource for such identifications... starting here: http://wetwebmedia.com/non-vert.htm Be chatting my friend. Bob Fenner>

Barnacles and specific gravity To whomever can help I was wondering about the specific gravity of barnacles. This is not a joke!!! It has to do with why a casino barge is now displacing more than it used to, and I am looking into all types of possibilities. So, do barnacles weigh more than the water they displace? If yes, how much? Thanks, Aaron Bloedorn <Hmm, likely at least two, three times the density of water... yes... when you remove them (Cirripedians) from boat bottoms they definitely sink. Bob Fenner>

Little insect things Hi Bob, I have a question about my tank (45 Gal.). Last week all of my fish died of Ick and now all that remains is a Blue Linkia,30lbs. of live rock and a Red Legged Hermit Crab. I am performing 10% water changes every week (which I should of had been doing in the first place) to have good water quality for the remaining species. I am not going to put any fish in my tank for 3 months and try to grow Coralline Algae. In this time frame will the Ick die off?  <Hopefully yes> I also notice in my tank these little insect looking things in my tank. They crawl around the substrate and glass. Do you know what might these things be and how could I get rid of them? <They're likely some sort of crustacean... maybe amphipods of some sort... look on the WWM site for the "Critter ID" link here for pix, descriptions... taking advantage of the lack of predators (fishes) and their remains... and will likely pass on their own during the three month fallow period. I would lower your spg and elevate temperature as detailed in the "Marine Disease" sections to speed this process along. Bob Fenner>

RE: Little insect things If I lower the salinity and raise the temp would that effect my live rock (coralline algae) starfish and hermit crab? <Good question... and not adversely if done slowly, systematically. See: http://wetwebmedia.com/martrthyposalfaqs.htm Bob Fenner>

Re: Copepods Mr. Fenner, Thanx again for your quick response! I'm glad to hear you will be @ the Superzoo on Sunday, that's the day we are going. What booth or exhibit will you be at?  <Just an attendee this time, walking the floor, chatting my poor friends ears off...> Or shall I just look for the crowd of people around you, asking questions. I hope we get to meet. My brother and I would be honored to buy you a couple of "little brown bottles". <Hmm, tempting for sure. Look for pet fish type with typical attire (shorts, short sleeve shirt, tennis... will have name tag... noisy> What would be the best type of goby to introduce into the tank to eat the copepods?  <One of the more hardy species... see: http://wetwebmedia.com/gobioidmars.htm and beyond> And will he live without a sand base in the hospital tank?  <Depending on what you choose no to yes happily> I have 2 weeks to go with the copper in the hospital tank. Should I add the goby next week when I get back? <I'd wait till the system is about done... other livestock almost ready to place back in main system> If you don't feel like emailing me back, I'll ask you at the show. Thanx so much. Craig <Be chatting, seeing you. Bob Fenner>

LITTLE FAST BLACK CRITTERS Hello Bob, I have finally set up a quarantine tank . It has been cycled for about 2 weeks now. When feeding the one fish that is in there I noticed food disappearing - being pulled into the crushed coral substrate. I continued observing and noted a little creature about 1/4 inch long. It was a dark color and almost looked like a shrimp. <Might be... or perhaps another crustacean> It moved very very quickly along the bottom and disappeared into the substrate. What is it and is it worth trying to eliminate? <Probably not... may help the system to keep clean, keep cycled... Bob Fenner> Thanks, Russ

Amphipods Hi there, Like some other aquarists, I also lost my population of amphipods, due to the introduction of a Mandarin Goby. I have since lost Mandarin Goby and will not get another one until I can set up a large size refugium. How would I go about to get the amphipods back? I believe I don't have any left. Can I purchase some kits such those sold by IPSF and InlandAquatics? My tank is a 60 gallon with about 75 lbs of live rock. Thanks. Chia <Yes to your question and your answers! The best approach is to buy these organisms for reintroduction, and the companies you mention are excellent. Bob Fenner>

Interesting Story First, Thanks for all of the advice you have given us over the past six weeks. The 80g tank is doing wonderful, seemingly better with each passing day.  <Ah, a delight, and a privilege. You're welcome.> All levels have been a consistent zero in ammonia, nitrite, and nitrate, and we have kept the calcium at a 450. Al of the live rock is a wonder to watch as the new life appears and grows. <Indeed> Since we put the first LR in 5 weeks ago, we noticed one of the pieces appeared to be hollow, with several holes less than half a dime's diameter leading to the inner chamber. We also noticed an occasional short leg moving small pieces of gravel from the interior. We put this rock in front to keep an eye on it, and because it appeared to have the most abundant growth of coralline, polyps, etc. Last night while doing my daily inspection, I noticed a hermit that had been in the same crevasse for a number of days. I thought his shell might actually be lodged in the depression, so I helped him out. It was not a crevasse, but a larger hole to the cavern inside, and I could see a large animal inside. Having finally dispensed with a mantis days earlier, I thought at first it was a full grown one. I had my wife mix up a batch of water into a large bowl, at a higher salinity than the tank, hoping to flush it out, but it was too large to fit through any of the existing holes in the LR. So, I slowly enlarged the hole from which we had just seen it. The layer was thin and it was easy work. As I touched its back, it scurried to the underside of the LR, so fast I thought it was a mantis. I carefully removed the LT and examined the underside, and nothing. I looked in the bottom of the bowl, and there was appeared at first to be a dark gray stone, roughly quarter-size, and maybe a 1/4" thick. I picked it up with a pair of forceps, and it is a crab. It must have been stuck inside this rock a long time. It has a smooth shell, and as I said, can fold up its legs and claws to look exactly like a stone. I put it into the aquarium, and it has burrowed beneath one of the other LR into the sand, making quite a nice place for itself shoving sand out from underneath. <Interesting> Any thoughts on what kind of crab this is? It has really been through the ringer, being stuck inside for so long. <Not really... would leave it be and enjoy it. Likely not a problem for now or the foreseeable future> Rick Farris See our pond at: http://pages.prodigy.net/rwfarris <Very nice pond and baby pix. Bob Fenner>

Please help! Strange Critters: Amphipods I Have a 90 gallon tank with Oscars and a gar that I feed pellets and live gold fish.. I recently noticed that the tank has thousands of small (very, very small) white worm-like parasites crawling on the glass. The fish seem to be parasite free, but I am very concerned. Do you know what these things are, and how to get rid of them? Please help! Sincerely, Robert Stone <Not to worry... these are very likely some sort of innocuous worm that is capitalizing on the lack of predators and food available from the messy eaters you have in the way of fishes... They will pass, become supplanted by other life forms... and you can keep their numbers down in the meanwhile by doing regular water changes and gravel vacuuming (like ten percent of the system every week. Bob Fenner>

Please help! More critters/amphipods Bob, Thanks for the fast reply. Are their any treatments to rid my tank of these parasites? I really don't like the idea of them in the tank. Any thoughts? Thanks again, Bob Stone <First off, these are not parasites..."living in/on another species where they derive nourishment, perhaps protection"... but simply organisms that are proliferating due to the circumstances listed... lack of predation and availability of space and food... just keep the tank clean(er) and they will go in a while or their numbers will be so diminished that you won't notice them... No need to add toxic chemicals, and their addition would hurt your fishes...Bob Fenner>

Agck! unidentified creature in my tank....  I have the oddest little thing in my tank. its a 55 gallon if it matters. I just got a scallop today and I was feeding it some brine shrimp when I noticed the most craziest looking creature vie ever seen. its about 4-5 millimeters in length and its 50/50 opaque/transparent white. I don't have a digital camera but ill try to make a description. it has a 'hood' at the 'front' and the hood goes back down the body where it turns into two tails that are more triangles than tails. it looks like the whole body tissue is one flat tissue that has been pinched in the torso to make the hood, much like the gulf war ribbons or AIDS ribbons people will wear pinned to their shirts. crazy.... in the middle where the pinch is there is a brownish body, the organs and whatnot. it goes about the glass of my tank by sweeping out its hood and then sucking in water to filter feed. then it pulls in its tail end to move. locomotion like a snail, but much less surface area on the glass. much less. I got live sand that caused a glass anemone problem and a lot of featherdusters, but I never expected this sucker. what is it? and is it bad? it looks rather sinister to me, but maybe that has to do with the sock of seeing it. thanks. Jon Trowbridge  <Hmm, sounds like some sort of crustacean (maybe even an intermediate form) to me... and very likely not harmful. I'd leave it be. Bob Fenner>

Crabby Hi Bob, I found a crab in my tank yesterday, that I never knew was in the  tank. I've had this live Fiji rock since March 2000 and never saw  him before. <Happens> I have a couple of questions, if you could please help  me out. Here's a description first. It resembles a common crab  (like a blue claw... yum) It's about 1 inch point to point, very  compact looking. The front(?) claws are very "stocky" looking,  they're not the long pointy type. The color is a reddish brown  with yellow along the joints of it's legs. Red eyes. The rear  legs have that "hairy" look the some crabs have. Now the Q's; 1- How big will it get? <Don't know> 2- Is it a threat to it's tankmates? (I've got an emerald crab,  15 hermits, a couple of stowaway snails and a mushroom rock) <Don't know the species or its propensities> 3- If so, what's the best way to get rid of it? (I don't think one  of my blue claw crab traps will fit in my tank) Any additional info would be greatly appreciated. Thanks for all  your help in the past. It's really helped me setup this tank properly...and I'm still waiting for "The Conscientious REEF Aquarist"!  I hope it happens soon... anyway, thanks again. Take care. Tony Revinski <Wish I did know to all... IF this sucker gets very big, or destructive, I would remove it... by a line tied to a meaty bait... sort of like those tasty Blue Crabs on the East Coast.... Be chatting. Bob Fenner>

Mystery crab Hi Bob. I really enjoy reading your column. I noticed a claw sticking out of a small hole in my live rock today. Upon close watching he seems to be digging a hole in the rock. He hasn't come completely out of the hole but I have seen a couple of hairy-looking legs sticking out. Can you tell me what this is and should I be concerned? Thanks. Walt  <<Hmm, may be a snapping or pistol shrimp... At this point I'd just watch, and enjoy this incidental livestock... If it gets too big, or "pinchy" you'll know... then I'd remove it. Bob Fenner>>

Copepod eaters Hi Bob, Is there any way I can get rid of what I think is a bloom of copepods in my 29 Gal. reef tank without destroying my corals and clean up crew? I can see them all over my glass; little white specks that move about. There are presently no fish in the tank. Thanks, Jim <<Oh yes... there are a number of mainly fishes that would really like to help you out... Do you have any wrasses to speak of? Interested in a Pseudocheilinus octotaenia? Maybe a Cirrhilabrus genus member? If one of these winners will fit in with your other livestock... this is what I would get.  Bob Fenner, whose survey of the wrasses, these genera, can be reviewed at the URL: www.wetwebmedia.com>>

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