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FAQs on Freshwater (and Terrestrial) Crustaceans, Compatibility, Control

Related Articles: Freshwater CrustaceansInvertebrates for Freshwater Aquariums by Neale Monks, Forget Crawfish Pie, Let's Make a Crawfish Tank! By Gage Harford

Related FAQs:  FW Crustaceans 1FW Crustaceans 2, FW Crustaceans 3, FW Crustaceans 4, & & FAQs on: FW Crustacean Identification, FW Crustacean Behavior, FW Crustacean Selection, FW Crustacean Systems, FW Crustacean Feeding, FW Crustacean Disease, FW Crustacean Reproduction & Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction, Freshwater Shrimp, FW Crabs, Terrestrial Hermit Crabs, & Marine Hermit ID, Hermit Behavior, Hermit Compatibility, Hermit Selection, Hermit Systems, Hermit Feeding, Hermit Reproduction, Hermit Disease/Health, & Crayfish FAQs, Crayfish 2, Crayfish ID, Crayfish Behavior, Crayfish Compatibility, Crayfish Selection, Crayfish Systems, Crayfish Feeding, Crayfish Disease, Crayfish Reproduction,

Some small shrimps leave fishes alone... larger crustaceans... Don't!

FW lobsters and crabs... in/comp.     2/1/11
Hello there,
Just a few questions if you don't mind, but first a short history.
I have an Electric Blue Lobster,
<Crayfish, not a lobster.>
he has been living in brackish water for a few months and seems to be doing great.
<Surprised, to be honest. Presumably not very brackish? SG 1.002 or 1.003?>
I had a Pleco and a flounder in the tank with him as well as several small feeder fish.
<Likewise, the Plec won't be happy above SG 1.003.>
The lobster himself has grown from around 2 inches to around 3 1/2 in the time that I have had him. The Pleco was around 6 inches at the time of his demise, the flounder around 1 1/2 inches at the time of it's demise. my lfs told me that the Plecos seemed to have difficulty with the water in our area!
<Least of your problems. Plecs aren't naturally found in brackish water, and while some may adapt to very low salinities -- they seem to have done so in the canals of Florida -- it isn't ideal. Flounders are a crap-shoot, and at least the sort sold widely in the US, Trinectes maculatus, is a subtropical species with a limited lifespan in tropical aquaria. It needs fairly brackish or marine conditions to do well. So let's say a water temperature of 15-18 degrees C/59-64 degrees F, with a specific gravity around SG 1.005 upwards to fully marine.>
#1: The lobster didn't bother the Pleco or the flounder for quite sometime, they seemed to tolerate each other. Is it possible that the Pleco died due to the water and the lobster made it a meal, got a taste for fish and went after the flounder next. ( he literally ate them both in a matter of a week)
<Crayfish will certainly eat anything dead. They are largely herbivorous in the wild, but they're also scavengers, with carrion being a significant part of their diet.>
#1.5 Is it safe for me to get another large Pleco to go in the same tank as the lobster?
<Crayfish are ALWAYS best kept on their own. You will never, EVER hear me recommend mixing them with anything else, certainly not fish.>
#2 I am so ashamed to say that just today I went to buy some feeders
<Do read about why feeder fish are bad:
There are almost no situations where they make your hobby better. Even putting aside cruelty issues, they introduce disease, they are too rich in fat and thiaminase, and they increase the risk of aggression.>
and came home with a Red Asian Crab,
<An amphibious, brackish water animal. Not suitable for aquaria.>
he was in an aquarium at the store and I wasn't told that his living conditions should be any different!
<Perisesarma bidens is the common species. Needs mostly land, with a pool of brackish water to bathe in. Not terribly hard to keep, but most die after a few months because of poor care. Completely unsuitable for cohabitation with crayfish.>
I am wondering how long he can survive in my aquarium? (while I set a proper one up for him)
<Hope this helps. Cheers, Neale.>
Re: FW lobsters and crabs    2/1/11
Thank you soooo much Neale,
<Glad to help.>
I will do what I can to clean up my act. And never again will I add to any of my tanks before consulting with WWM first.
<No need to go quite that far, but we are *free* and we do try to answer questions within 24 hours, so if all else fails, ask your retailer to put aside any beastie you're interested for a day or two, and drop us a line.
Do also spend some time searching the WWM site -- there are few things we haven't answered at least once before!>
<Cheers, Neale.>

compatibility   11/24/10
Hello, I was wondering if ghost shrimp, Amano (algae eating) shrimp and fiddler crabs would be compatible with each other. I know fiddler crabs require brackish water, but what salinity can the shrimp tolerate? If they get along, what SG would be best for all species? They would be in a 30 gallon tank. I would provide sufficient habitat/hiding spots for all species including water plants for the shrimp and adequate land for the fiddler crabs. Thanks.
<Funnily enough Amano shrimps develop in the sea, but the adults mostly live in freshwater. But they will tolerate slightly brackish conditions just fine, certainly SG 1.003 to SG 1.005 at 25 C/77 F, and perhaps a
little higher. In fact most shrimps tolerate slightly brackish conditions, and I have some Cherry Shrimps in a tank at 1.002 at 25 C alongside some Limia nigrofasciata. But Uca species may need more saline conditions depending on the species. Plus, Uca are opportunistic, and while their diet is primarily algae and organic detritus sifted from mud, they may catch shrimps given the chance. So by all means try it out and see what happens, but don't invest a huge amount of money in this just in case it doesn't work. I'd try out the brackish water Palaeomonetes sold as live food -- at least here in England -- before investing in more ornamental shrimp species. Cheers, Neale.>

Need some direction (FW, possible unwanted cladoceran) 2/25/09 Neale? <Yes...?> I'm perplexed and need some direction and encouragement. I have a 20 gallon FW tank stocked w/ a dwarf Pleco and 10 glass fish. All but one of the glass fish was just added a couple weeks ago. Current water parameters are: 78 degrees, 0 ammonia, 0 nitrite and ~ 20 nitrate (I know. more frequent water changes) and above 7.8 ph due to municipal water supply. <Sounds good.> All was good until I noticed during a water change last week that small white specks would enter my gravel vacuum during vacuuming. They purposely returned to the gravel. I initially thought they were just non-living specks from who knows where, but then looked more closely and they appeared to be swimming freely in the water - darting here and there, really. If they were located on the fins of my stock, I'd definitely treat for ich. But they aren't. Interestingly enough, I noticed this only one day after adding frozen brine shrimp to vary the glass fish diet. All the fish appeared fine, so I dismissed it (.mistake). <Harmless. Have them in some of my tanks.> NOW they are taking over the tank - there have to be thousands of them. Again, they are free floating. NOT on the inside of the glass. From your site, I'm assuming they are cladoceran (aka water fleas). If so, Bob Jenner says they will run their course in time. But the glass fish are absolutely miserable with them, as they cannot relax and just hang out. They dart all over, nipping at one another constantly. Another interesting development is that my Pleco is out of his cave during the day more in the last week than I ever remember him - very odd. And when looking closely at the fish tonight, it appears that the white specks are now attaching themselves to the glass fish, mostly at the tips of the top/lower fins. So I started treating w/ ICH tonight w/ a two-day course just in case. <If they are crustaceans, then any copper-based medication should kill them. On the other hand, blooms of them aren't common in aquaria, and suggestive of a deeper problem. To multiply, they need food. This may be algae if you have a lot of light (including sunlight) but not enough live plants. It might also be faeces and uneaten food. If the tank doesn't have adequate mechanical filtration (essentially, current + rinsable media) then organic wastes will accumulate in the gravel, and that in turn will feed these "pests". Get rid of the food source, and their populations will quickly drop.> Does my explanation of them coincide w/ cladoceran or anything else you know? If so, how can I nip them in the bud? The LFS wasn't familiar with anything I was describing, nor had a microscope to look at my water sample, but thought maybe adding some stock that will eat on them could help control things. They suggested molly or tiger barbs. I'd hate to add anything at this point until I figure out what the heck is going on. Thoughts on their recommendation? <If this was really tiresome, and given the tank is fairly small, I'd perhaps recommend a "reboot". In other words, put the fish and some water in a bucket. Stick or connect the filter to the bucket, so that it is running. Remove everything else from the tank. Deep clean the gravel with lots of hot water, or else throw out and add new gravel. Put the tank together again. Acclimate fish to new water conditions just as you would if you'd bought them, but don't directly add any old water to the tank. Reconnect the heater, filter, etc. Sit back, knowing a job well done. All else being equal, you'll be starting from a normal baseline except that the filter is 100% mature. Any "pests" that get in there will have to go through you now, so review any plants or live foods, and take care to keep on top of hygiene. Clean the gravel, remove uneaten food, etc.> HELP!!! I want to glass fish to relax. they are getting really stressed out. THANKS as always. Gosh - how could I do this without you all at WetWeb?! Kristi <Well, I hope this helps, and thanks for the kind words. Cheers, Neale.>

Let's get ready to rumble! Non-indigenous crusties duking it out in the U.K.  10/15/08
Here's a link to a story about the Chinese mitten crab and the North American crayfish in the UK.
The gist of the item is that these two animals have been extending their ranges across the British Isles having been introduced in the last century. The crab has been working its way upstream from the Thames Estuary, while the crayfish has escaped from crayfish farms inland. It now appears they're set to meet one another, and in the absence of any other predators or competitors on these islands, they may well turn on one another as they compete for space. Both are territorial omnivores and both use burrows in muddy banks for shelter.
My money is on the crab; having worked with other crab species over the years, I have learned never to underestimate their aggressiveness and versatility. While the video is in the usual BBC style of appealing to the lowest common denominator, it is rather fun to see these two animals up close.
Cheers, Neale
<A well-made short doc... I'll go with the Cray here... soon to be seen on the WWCW federation (C for crustacean)! BobF>

Compatibility of FW crustaceans with fishes  12/30/2005 Hello I have a couple of questions First I have a 40 gallon freshwater fish tank setup and it has been running for about a month. I have in the tank a red tail shark, 8 tiger barbs, 1 clown Pleco, 3 golden barbs and 3 blue coral Gourami dwarf . I don't want to add any more fish but I was thinking I wanted to add a couple Singapore Flower Shrimp and may be a Hammer Cobalt Blue Lobster. So my questions are A) will the shrimp be safe with the fish that I have? <Likely so, yes... as long as it has some hiding spaces... dense plants, rock caves... to get out of the way during molts> B) If I was to get the lobster would my fish be safe with the lobster? <Not if the lobster is hungry... if kept well-fed, perhaps. Bob Fenner>

Crustacean for a Community Tank - 05/21/2006 Hello folks, <Hello, Doug.> I've been reading your articles with interest but I still am unsure about what I should do with regard to finding a suitable crustacean for my community tank. <Someday we'll have a shrimp article up....  just (finally) wrote the thing.> This is a freshwater tank, 20 Gallons, 2+ years old, nice and stable. Right now I have 5 Rasbora tetras, 6 cardinal tetra's and one fairly large Chinese golden algae eater (5" long). We added the Cardinals a month or so back and they are doing fine. We wanted to get some kind of crustacean to complete our community but are not sure what would be best after reading about predation of tank mates. What do you think might work in this situation? <LOTS and LOTS of options....  Any shrimp from genera Atya, Atyopsis, Caridina, or Neocaridina....> I had thought of a Hammers cobalt blue lobster but after reading more about it realized that it would probably be the sole tank occupant in short order. <It would.  Stay away from any crayfish/"lobsters".  If you want something big and beefy, for a 20g tank, maybe look for Atyopsis moluccensis, the "bamboo" or "wood" shrimp.  A 20g tank is suitable for a male and a few females.  Or if you want something bright and tiny, look for "cherry" shrimp (Neocaridina denticulata sinensis v. red), "Rudolph"/"red-fronted" shrimp (Caridina gracilirostrus), or maybe "crystal red" shrimp, (Caridina sp.).  There are plenty of other small shrimp species that are less colorful, and most any would be of use here.  I do hope you are able to find a fun and pleasing pet to add!> Thanks for your advice.  -Doug <Glad to be of service!  Wishing you well,  -Sabrina>

Question regarding Triops in a planted tank  1/29/07 Hi Crew, <Emma> Just recently I discovered the absolutely bizarre but strangely adorable Triops < http://www.triops.com/what.htm> and I would love to keep them in one of my planted tanks. All the information I have found on them seems to be rather scant or contradictory - some sources say they will eat all your plants, some don't even mention it. I have also heard that they love to dig - which could be a problem as I have a topsoil underlay. <Mmm, will dig a little... do eat soft parts of many types of plants> Also many gallons does a fully grown Triops need? I'm talking about the smaller (2 - 4 inches, I believe) American variety. <Please see the link above> Is it possible to keep them with goldfish, or will they harm them? <The larval forms will likely be consumed by the goldfish> Thank you for all your help, Emma <Bob Fenner>

FW Round, Tan Bugs? Hello <Hi Jodi> I have a question about an infestation in my aquarium.  I have a 75 gallon freshwater tank.  I have one big Oscar in it.  I noticed on the walls of the aquarium it looked like it had white hairs on it.  So I got to looking a little closer and on the gravel there are tiny round tan in color bugs.  I'm not sure what they are and how to treat the tank.  If you could help me I would really appreciate it.  Thanks for your time.  Jodi Hedden <Likely some sort of crustacean... and hopefully not a variety that will attack, parasitize your livestock. First off, I would take some of these bugs into your fish shop and ask them to take a look, give you an eyewitness identification as to species/group... Next, a thorough gravel vacuuming while changing part of the water (maybe 25%) once a day... till they are no longer visible may cause them to disappear... And if you find these are a bother still, there are "economic poisons" sold as fish remedies (ones containing Masoten, Dylox, Neguvon...) that you can add that will specifically wipe-out all arthropod life (hopefully you don't have crayfish et al. as pets). Please read here re this last: http://wetwebmedia.com/PondSubWebIndex/contrpdparasit.htm I would NOT use other more general biocides (e.g. preparations that contain formalin/formaldehyde...) as these are too toxic, dangerous to your other life. Bob Fenner>

Ostracod Anomaly - 08/05/2005 Hey, thanks for a great and informative site. <Glad you enjoy it!> I just have a problem with Ostracods in my tank, they just appeared out of no where and it doesn't seem like there's a solution to this problem. <I recall when I was quite young, I had a small tank with renegade snails, and had the same problem.> Is there a way to get rid of these with out harming my plants and shrimps? <Reduce their food source - vacuum substrate heavily to get decaying materials out, feed significantly less, remove dead plant leaves if any, and perhaps try to find a fish that will make a meal out of 'em.  I've used Gourami to control aphid populations on floating plants; possibly dwarf or pygmy Gourami would consider Ostracods edible....?> Thanks, John <Wishing you well,  -Sabrina>

Ostracod Anomaly - II - 08/07/2005 I actually don't know what is causing it, its not the food source, I only feed my shrimps a little 2 times a week. Thanks. <I wonder if perhaps they are feeding on plants or decaying plant material, or possibly algae....  Again, it might be worthwhile to employ a small predatory fish in this system and see if that controls the population.  Wishing you well,  -Sabrina>

"A Craw-Fish by any other Name would Chew Plants..." Mr. Fenner: I am in the early stages of preparation for building my first community tank. I am planning a 35-Gal tank with many live plants and two species of schooling middle fish, one species of surface fish, and an additional species of bottom-feeding/Pleco-type fish. Is this feasible? <Sure> My main concern is this: I feel that in the future I may be unable to defend myself against the irresistible charms of lobsters and crayfish.  <They are delicious... prepared properly!> Is there a place in a perfectly harmonic community tank for one of these invertebrates? <Mmm, no, not really. There are some fresh to brackish crustaceans that are "better"... please read: http://www.wetwebmedia.com/shrimpfw.htm> I hear that they have picky tastes in water pH and temperature, are destructive to aquatic landscaping, and can be determined to bust out and go AWOL. Is there a way to have fish AND yabbies? <Again... not really... their tastes are actually "too cosmopolitan", and many species are known to be quite "eury" condition... adaptable to widely varying conditions... but most all what folks call "lobsters", crayfish, crawdads, ditch "bugs"... are all too destructive, fish-eating to be "harmonious" in a community tank... Maybe two tanks? Bob Fenner> Please advise.

Crayfish Starting from scratch here.  We have success in sustaining crayfish.  We have had zero success in growing the tank population.  What could we be doing wrong? <Likely the ones there already are eating each other. Especially when they molt (shed their external skeleton, to grow) crayfish are very susceptible to predation. Maybe adding more rockwork, some plants (plastic or real) will help boost your population. If you're expecting them to reproduce, there are a number of reasons why their young may not be being produced or likely being consumed as well. Bob Fenner>

My Little Lobster (terror!) Hello, I hope you can help me! I recently rescued what I believe to be a lobster from a friend who had moved it to a TINY tank after it removed the tails from all of his fish! It is about 3 inches long (when my friend bought it he was told it would grow to about a foot long) and resembles a crayfish at the moment but has a bluish tinge to it. My clever friend seems to know nothing about its care and I have spent the day searching bookshops and the web for info on how to care for it with no success. So I basically need as much info as possible or recommendation of a good book (which I can get in the UK). <Mmm, sounds like a Cherax species. Please see here: http://www.wetwebmedia.com/FWSubWebIndex/fwcrustaceans.htm and use the names given for the identified animal a spin (insert) on your search engines. Bob Fenner> Thanks very much Sarah

Crayfish and goldfish in ponds Hi, Do you happen to know if a crayfish would be good in an outdoor pond? Or would it eat my goldfish? Zac Lohrenz <Gage is apparently incognito... depending on the type of crayfish, size of goldfish... it might indeed be eaten... though I have seen these two species kept together. Bob Fenner

I don't want copepods! FW crust. control.   3/15/08 Hi WWM, I've searched your website for 2 weeks straight for information on eradicating copepods, but to no avail. Any info I find is in regards to how great they are and/ or how to cultivate them. I know that they are beneficial for fish to eat but i have what seems like thousands of them and i don't like them. Plus none of my fish eat them. I have a 75 gallon tank with 1 managuense,1 male and 1 female Dempsey, 1 green terror, 1 fire-mouth, and believe it or not live plants. I know that's too many big fish for a 75 but I will be transferring some to another tank when they get to large or aggressive. 0-Ammonia, 0-Nitrites, 10-15 ppm nitrates. 1 Marineland C-360 canister, and 1 Penguin 350 H.O.T. filter. I have so many copepods that it affects the water clarity. They are floating around everywhere. I do one 25-40% water change every week depending on the time I have. I want to know how to get rid of them without harming my fish. I know that some fish will eat them but my cichlids probably won't be too welcoming to any newcomers. Thank You very much. P.S. Your site has a plethora of knowledge, and it's great for novices like me. <Greetings. If you have so many copepods that you can see them, you likely have serious water quality problems as well. Truly, they will only multiply to big enough numbers to cause problems if they have lots to eat. Since they feed primarily on algae in the water column, your tank needs to be receiving lots of light and/or have high levels of nitrate and phosphate. Moreover, if the mechanical media isn't removing them physically from the water as it passes through the filter, then you don't have enough filtration. For large cichlids you should using filtration generating turnover of not less than 6 times the volume of the aquarium per hour. So add up the gallons per hour filtration for your filters and see if they exceed the magic number of 450 gallons per hour. I'm not a big fan of "hang on the back" filters though I understand they are for some inexplicable reason popular in the US. By gripe with them is they always seem to be a lot of plastic and plastic media modules but not a whole lot of actual media for their size/turnover. For messy cichlids, it's hard to beat standard issue external canister filters. In any case "the fault is not in our stars but in ourselves"; in other words, don't go after the copepods but try to establish why they're doing so well. Even if you somehow killed them off, for example with a copper-based anti-crustacean parasite medication, they'd likely come right back again after a few months. Cheers, Neale.>

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