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Crayfish, Crawdads, Ditch Bugs Stocking/Selection

Related Articles: Forget Crawfish Pie, Let's Make a Crawfish Tank! By Gage Harford, Invertebrates for Freshwater Aquariums by Neale Monks, Freshwater Shrimp, Crayfish, "Lobsters", Prawns Freshwater to Brackish Crabs

Related FAQs: Crayfish 1, Crayfish 2, Crayfish ID, Crayfish Behavior, Crayfish Compatibility, Crayfish Systems, Crayfish Feeding, Crayfish Disease, Crayfish Reproduction, Freshwater Invertebrates/Use in Aquariums, Freshwater Crustaceans for the Aquarium, FW Crustaceans 2, Fresh to Brackish Water Crabs, Hermit Crabs

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Dwarf Crayfish, comp.     7/15/13
Hi there!
I currently have a 55g planted tank inhabited by eight Harlequin Rasboras (max 2 inches) and two Yellow Tail Spiny eels (Macrognathus Pancalus, max 7 inches).  I do intend to double the amount of Rasboras and get a school of Dwarf Neon Rainbowfish (max 3 inches) eventually.  I am looking to add some interesting bottom dwellers to my tank that will get along with the eels and not out-compete them when feeding time rolls around.  I was hoping that a few Dwarf Crayfish (Cambarellus patzcuarensis) might be suitable companions.
<Mmm, I'd look into catfishes of various sorts instead... too likely your Mastacembelids will tussle with, eat the Crays>
 I have read that they remain small (1.5-2in) and are neither aggressive nor nocturnal, though there seems to be a bad stigma attached to mixing crayfish and fish in general. 
I was wondering if you might have any experience with these small invertebrates as well as whether or not they would be peaceful AND safe from predation in this tank.
<Not with this species; but extensive with some Procambarus and Astacus spp.>
 If these dwarf crayfish are indeed a poor match for the eels, can you recommend a suitable and/or interesting alternative bottom dweller?
<There are MANY... Siluriform/Catfish choices... I'd have you peruse our Cat area; see here:
scroll down; read the "Compatibility" and "Stocking/Selection" FAQs files>
Thank you for your time,
<Welcome. Bob Fenner>

Procambarus Clarkii, stkg. comp.     2/25/13
I purchased seven large Procambarus Clarkii a few days ago and placed them in a 55 gallon aquarium.
<Mmm, I did a report in college re this species "substrate size preference" and have kept them as pets, and eaten quite a few at "crawdad bakes"...
They will attack and eat each other... till there is an ongoing balance re space, hiding areas and food availability>
The aquarium has aeration, filtration, and places for hiding.
On the second morning I noticed that one of the crayfish had been half eaten.
 The tail was eaten first then the rest of the crayfish was consumed over a 24 hour period.  The next day I noticed two more met the same fate.
<AH yes>
I have provided food in the form of vegetables and shrimp every day. I am becoming concerned about this behavior because I have lost 3 of the original seven to date.
I would like to know what is causing this behavior and how it can be prevented. Any help that you can provide would be greatly appreciated.
<Tis natural... folks who raise this species for human consumption purposely add fertilizer, make conditions that obscure water clarity, to reduce this sort of aggression. I would add more clay flower pots, PVC pipe/parts et al. to slow down the rate of attrition. You may be "at it" w/ the present stocking level. Enjoy the remaining individuals>
<Bob Fenner>
Re: Procambarus Clarkii, stkg.      2/26/13

Thank you for your help. I have modified the environment and hope this will correct the problem.
<Ahh; I do hope so. B>

Florida blue, too much stress?     1/12/13
Hello, Sylvi here!
<Hello Sylvi,>
I have a major problem with my female, Orion. She came to me with one claw smaller, obviously slowly regrowing.
<Correct, and may never reach full size. Crustaceans don't moult to order. They moult periodically as they grow. They moult frequently when young; infrequently when sexually mature. Eventually they all but stop moulting altogether. So, if your crayfish is fully grown, it may moult only every few months, in which case the claw will always be relatively small.>
I noticed her carrying a bundle of eggs a few days ago (I'm not sure how fast the laying process is, I was very surprised to suddenly see "her" with eggs). Last night, my large male Boris was really restless and constantly trying to invade Orion's safety cave, even though his regular cave was empty along with two other caves. This morning I found Orion cowering in a corner, her regular claw ripped off, by Boris of course.
<Hmm… confused here. Why are you keeping them altogether? Standard operating practise is to keep crayfish one to a tank. If you keep multiple specimens in one large aquarium, then don't go naming any of them -- because their lives are likely to be short and brutal. What more to say? Understand that crayfish aren't sociable animals, and keep them accordingly. Kept in solitary, 5-10 gallons per specimen, and such intraspecific aggression, even cannibalism, will be avoided. Simple.>
I separated her from the other two large males, leaving only a two inch female, and a one incher, with a few fish to keep the balance. My concern is, with only a smaller regrowing claw, carrying eggs, and having a claw ripped off, will she survive this trauma along with her eggs??
<Wouldn't put money on it. Crayfish are largely herbivorous in the wild, but they are completely opportunistic as well, so anything dead or weak is on the menu. Being nocturnal, we rarely see them doing much, which is why people often say things like "my crayfish is completely peaceful, it ignores all its tankmates". People can say that, but it isn't true, and unless you're watching your crayfish with night-vision goggles, you really don't have any idea what your crayfish are doing.>
I've been trying to feed her some greens, bloodworms, defrosted feeding fish, and brine shrimp, but i haven't seen her eating yet....so I'm very worried right now. Please tell me what I can do to make her as comfortable as possible and have her eating again! Thank you so much!
<Easy. Keep her on her own. Problem solved. Once in such an aquarium, she will recover if not too far gone, damaged.>
PS: The two inch "female" Rorschach started carrying eggs about 10 days ago, but I noticed her reaching back and snacking on her own eggs as if they were M&M's, and currently she only has about 5 eggs left, but they are a strange light brown color. Is this why she ate them? Or the other way around?
<Stress causes female animals to do all sorts of apparently odd things. But in terms of biology, eating your young makes complete sense if you are so stressed you know for sure your young won't survive. By recycling the energy put into those eggs, that female can conserve that energy for another occasion. Again, keep crayfish singly. This has been gone into over and over again, and yet people do try to re-invent the wheel when it comes to crayfish keeping. They just aren't trustworthy, sociable animals. If you keep a group, expect fatalities, and don't be surprised if you end up with a single, big male. Cheers, Neale.>
Re: Florida blue, too much stress?     1/12/13

I should add, I was keeping the 2 inch female Rorschach, 3 inch female Orion, 4 inch Boris, and 4 inch Godfather all in a 10 gallon tank, along with a 3 inch Chinese algae eater male, Bobby, who stands up to the large male crayfish like a large black Spanish bull, also a 1.5" playful yoyo Botia, who strangely befriends everyone and takes turns sharing caves with the crayfish and Bobby, plus 6 zebra danios. Soooo yes, a bit too much for one tank, but everyone lived in peace.
<So far…>
I keep the temp 65F - 75F, have a pump and bubble stones, lots of caves to go around, and do 50% water changes every week. I treat the water weekly with conditioner and Cycle, as well as aquarium salt. Water check hasn't been done in a few weeks, my bad. Iodine I just found out about reading through your website. I now have a 25 gallon beside the 10 gallon making sure there is no overcrowding. I use coral/gravel for the bottom, but do not have live plants. (I am also wondering if it is safe to buy potted indoor thick bamboo, let it root out in the gravel with some waste/food in the aquarium water, and then add it to my aquarium.
<Has been done, yes. But beware "bug sprays" used on houseplants -- these can be lethal to fish.>
I see thick bamboo in closed off small decor aquariums with small fish and African dwarf frogs, the waste keeping the bamboo alive, the bamboo adding necessary nutrients to the water, which keeps the water clean and the critters happy…strange.
<And also unlikely. Bamboo doesn't add anything to the water that's helpful and while plants can remove ammonia from the water, whether they actually "clean" the water is debatable in most aquaria. For that to happen the ratio of plants to fish has to be very high, and the plants have to be growing very fast, by which I mean you're cropping back the plants (i.e., pruning) once a week.>
So back to the bamboo question...safe or not?) The aquarium diet consists of tropical flakes, chopped small fish, brine shrimp, bloodworms, frozen green peas, cucumber, and zucchini to keep everyone happy. Sinking pellets didn't work well since they dissolved too quickly and sunk into the gravel if my crayfish weren't hungry at the time, same with sinking crayfish pellets. I will do water tests, add iodine, sushi Nori asap, but for now my main concern is the wellbeing of Orion with her eggs, lack of appetite, left with only her small claw, suffering great trauma last night. Thank you so much!
<Sylvi, it's time to do some reading. Start here:
Crayfish shouldn't be kept together if you want more than one specimen to do well/survive, and crayfish shouldn't be mixed with fish. Cheers, Neale.>
Re: Florida blue, too much stress?     1/12/13

Thank you for all of the help Neale/crew, and the very quick response!
I'm making major changes currently, and I guess I have to give Orion a few days to see if she starts eating, as obviously the stress has been great on her. The reason I kept all my crayfish together was because they were given to me by a friend who has had them in large communities, constantly reproducing for years in a 40 gallon cube tank, along with some tropical fish.
<Ah yes, often happens. And it a big tank, you can get lucky. But crayfish aren't reliably sociable or peaceful, so I'd never recommend them as such.
To be fair, there are one or two exceptions, species of crayfish that seem "better" than others.>
And of course LFS staff are not helpful at all. I heard everything from "peaceful community crayfish" to "two per 10 gallon tank can thrive for up to 20 years".
<I see.>
When reading up on the Florida Blues, that was when I realized I will need a bigger/more tanks to house them all. They seem to have a wolf-pack system though. The largest male was the "Godfather" until the other male Boris took over the role after a battle, which thankfully only resulted in Boris losing an inch of his left antenna, and Godfather having a small piece clipped off of his right claw.
<Sounds about right.>
I wonder if maybe I've been lucky so far which no cannibalism due to the conditions they lived in at my friend's 40 gallon aquarium holding about 40 crays?
<Can be. Overstocking tanks is interesting. While it causes problems in terms of water quality, it does prevent any one fish (or crayfish) getting the chance to establish a territory. Any individual who tries will have to constantly fight all the other crayfish, and he'd never make any progress because all the others are doing the same thing to, and there's no peaceful cave or corner he can defend consistently. Kind of like how when people are on board a crowded subway train the usual rules for personal space are ignored. Anyway, if you have a large group in a reasonably big aquarium with adequate filtration, a sort of status quo is maintained where none of the crayfish becomes dominant. Take five of those crayfish and put them in their own tank and suddenly the rules change. There's now a chance for the strongest specimens to become the boss because he will be able to claim his corner and manage his aggression adequately well, only having to fight the few other crayfish occasionally.>
As for the fish, I added them to the tank in a span of two weeks before the crayfish arrived, with Bobby, the aggressive Chinese Algae Eater protecting his territory, which seemed to work. He stands up for himself and for his new mate, another Chinese about the same size.
<Do read up on Chinese Algae Eaters, which are not from China and don't eat much algae. Properly known as Gyrinocheilus aymonieri if you want to look online about them, they're big fish (20-30 cm/8-12 inches within a year or so) and as adults can be extremely aggressive.>
He also is very protective of Nighthawk, the playful Yoyo Botia, scaring off any of the crayfish that wander too close to their caves.
<I doubt he's actually protecting the loach. They may have common cause at the moment, but long term the chances aren't good they'll get along.
Interesting, the Yoyo Loach (Botia almorhae) is a good community species, and a social one, so you'd be better off keeping 5 of them in a tank upwards of 150 l/30 US gal.>
I have had them in the 10 gallon with the Zebra Danios for about 6 weeks, only having one Zebra killed, and one injured.
<That's actually not a very good track record, one dead fish, one injured fish, and various crayfish injuries.>
So, I think my tank has been installed with some Luck o' the Irish!
<No such thing as luck. At least, look at it the other way. Playing Russian Roulette once and surviving doesn't make it a safe game.>
But now I think I will be safer with 30 gallons for the 5 crayfish, two of which are still adolescent. If I have luck and have hatchlings, I already have a LFS who has a hard time shipping in Florida Electric Blue Crayfish, willing to buy all the surviving hatchlings once they are 3/4" in size. So, I am happy they will have a home to go to.
So, I think I have taken the right steps and am now prepared to keep a safer environment for my tankmates. Last step will be the Iodine on my next stop to the LFS. On a final note, when cleaning the tanks, I do a full hand/arm sterilization as I was required in science/medical labs, and gently usher the crays into my cupped hands to transfer them to the temporary bucket.
<Good personal hygiene/safety when working with aquaria is always a good idea.>
They seem to be fine with this, and I am confident that with the thorough scrub down/wash of my arms and hands, I provide no potential harm or infection to them.
<To be fair, the risk is mostly the other way. Aquaria are commonly infested with things like Salmonella wherever bits of food can decay in warm, moist areas. The only real risk going the other way is if your arms are soapy and that soap gets into the water as that can cause serious harm.
As a general rule, it's also a good idea to clean nets, buckets, etc. or at least let them dry out thoroughly as/when taken from one aquarium to another, as wet objects can carry parasites (like Whitespot) from an infected tank to a clean one.>
Also, I feel that this is a safer transportation method then the net or the pinching in the middle, as this way there is no danger of a struggle ending up in an injury. Does this seem safe enough for the Crayfish?
<Likely so. These animals aren't delicate at all.>
Once again thank you so much for the time and energy you and your staff put into helping out all these hobbyists, and I sincerely apologize for not doing enough research on my part, and for the many badly written and very brief emails and texts you and your crew receive. I can only imagine how irritating this must be on your part. Thank you very much Neale, for all your help and useful information, it is much appreciated! And I hope your weekend goes well, and you have a chance to sit back with friends and enjoy a cold one or two at a nice pub or at home!
<I hope so too! Good luck, Neale.>

Tubifex worms, Polypterus palmas, lobsters, tetras... Crayfish stocking f' I guess     2/11/12
Dear Mr. Bob Fenner,
<Hey Ben>
Happy to know that you're coming to our country. Please let me know when you're going to visit Jakarta, if time permits I'd like to buy you lunch!
<Will do. The event is off to the east, Borobudur: http://www.interhash2012.com/>
It is written in your Bichir FAQ that live feeder fish could become a source of parasitic infection, and so I decided to find an alternate food source for my Palmas. I tried Tubifex worms. Works like charm, for now, as you can see from the pictures, now the Palmas quit bothering the tetras, and they don't even bother some river shrimps which I put in yesterday. Thank you for your great advice.
I put in a small red lobster this morning, and am happy to report that the lobster and palmas are at peace, at least for now.
<For now>
The lobster also does not bother the smaller shrimps, and ate only the dead ones.
Some of the shrimps somehow got sucked into the filter and died there, and the lobster calmly munched on their dead bodies. The tetras (both the Neon and the Rummynose) seems to be able to avoid being sucked, and they're very happy now because the Palmas prefer to eat the Tubifex instead of them.
What are your thoughts about my current system? Could this be improved? Would this peace last? I included the pictures for your viewing pleasure.
Thank you for your kind attention, and I wish you a wonderful weekend!
<And you. BobF>
Ben Haryo

Crawdads in my pool   5/10/11
I let my swimming pool go over the winter and it was very green and nasty when we cleaned it last weekend. It was chock full of crawdads (like 500) and 1 frog.
My question is how did they get there?
<Mmm, crawled/walked and hopped likely>
I could see the frog (and occasional turtles) because they are mobile. We have a canal about 80 feet from the pool.
<This will do it! Cheers, Bob Fenner>

FW Crawfish?  11/6/08 I am looking for a certain type of algae eating "freshwater blue Japanese lobster" for a friend of mine who said he used to have a few in his planted aquarium.... he claimed they were some holy grail algae scraping machines.... however any crawfish I have ever observed seem to scavenge and hunt (smaller fish, crustaceans, anything meaty...) SO... The only animal I can find via Google are "Cambroides japonicus" ....Not so sure about them... if I could read the Japanese script on the pages it might help me more... Thanks for all your help!!! You Guys Rock!  Mitch (ps. I am trying to obtain possible photos) <Hello Mitchell. So far as I know (and can understand) no crayfish is a useful algae eater. Yes, they all eat algae, but they do so by processing sediment. I can't see how these hulking animals could possibly scrape glass or delicate remove green fuzz from soft plants. Most crayfish are more like to eat plants than clean them! There are Japanese shrimps that have been popular as consumers as green algae, called Amano Shrimps. I personally consider Nerite snails to be far superior (see my article on Algae Eaters in this months PFK magazine for a full run down of algae-eating animals). But do also understand that NO ANIMAL fixes a major algae problem. At best they consume certain types of algae, but since all animals also produce ammonia, they fertilize the water, speeding up the growth of algae generally. The ONLY reliable fix for algae is to add fast-growing plants under bright lighting. When aquarists report that their planted tanks have no algae, this is rarely because of the fish or shrimps or snails. It's because the plants are stopping algae from growing through a process called allelopathy. If your tank [a] doesn't have fast growing plants; and [b] doesn't have bright lights, then adding an algae-eater won't make much difference and could make things worse. If your tank already has brown algae, hair algae, or blue-green algae, then you have other problems with the tank, and adding a crayfish or algae-eater of any other kind isn't on the cards at all. Cheers, Neale>

Red claw crayfish, sel., beh.   6/4/08 Hi! I was just wondering about keeping red claw crayfish, Cherax quadricarinatus, and have been reading on WWM about keeping them. I was just wondering though, how interesting are they compared to other crayfish? I have a Louisiana red P. clarkii and I find her active and always walking about. <Yes... I've kept this species off and on for years... very interesting IMO/E> Are red claws a lethargic type of crayfish spending most of their time hidden? <Much more than Procambarus> Plus some places I have read says they are not very aggressive towards their own kind, while other places say they are always on the lookout to murder each other. <The genus is more like the latter in my experience> Have any of you had any first hand experience with keeping these critters? <If hungry, crowded...> Thanks! Don Smith <Welcome. Bob Fenner>

Misalanious crayfish in the tank :/ -04/11/08 <Misalanious? ...must be a new genus. ;-)> I have a piranha he's about the size of a small plate, anyways...I was wondering if a crayfish can leave eggs behind after they're gone? <I doubt it was an egg. But if you've been putting adult crayfish in your tank, then it's possible that one of them was still carrying a baby (or even several) which you just didn't see.> I haven't had crayfish in my tank for a couple years and i just noticed one about a cm in length (it's so cute! :D). It looks as though it's been in the tank for quite awhile...It's got a home built underneath an ornamental log. I was surprised that the piranha hadn't eaten it, if it has been in the tank for a while. I'm sure it could have also been scooped out of the comet tank at the store...? <This is another good possibility. At the LFSs where I've worked, we'd find all kinds of things occasionally mixed in with the comets/feeder fish or even in with the ghost shrimp.> I'm Baffled! :/ I just threw a shrimp pellet in and it's been clutched to it ever since :) We'll see how long it does last though. <Best, Sara M.>

Classroom Tank >Hi crew! >>Good morning, Joy, Marina here. >One of my students took home the class pet for summer vacation, renamed her, and now my red eared slider has a new home and I have a 55 gallon tank to fill.  Help!!  I've purchased an aquarium divider.  I want to know can I have a crayfish or lobster on one side of the divider and a shrimp and some type of aquatic or semi-aquatic frog on the other.   >>Yes, you can do this. >Possibly a fish or two if you can recommend ones that won't be eaten. >>Not with the crawdad/freshwater lobster, but if you have something like a small leopard frog on the other side, then you can put in mosquito fish or similar small fish.  Also, consider land hermit crabs (the Caribbean variety).  I don't think they can pinch any worse than a crawfish!  They do require a different setup, though.  If interested, check out http://www.hermit-crabs.com for best information. >My concerns are having species that have the same temperature and water hardness requirement. >>Not exactly a worry with frogs and crawdads, very hardy, as are most commonly available tropical fish. >Some of my students have vision issues, so could you please recommend colorful species (our school uniform colors are white and blue, I would love to say my aquarium creatures are dressed in uniform). >>Sorry, but most colorful species are VERY specialized and difficult to care for, and the ones that I can think of that would match your school colors are poison dart frogs.  Even though their stay in captivity and lack of variety in diet seems to seriously reduce toxin levels, still not a good idea in my opinion (mostly for meeting their requirements).  There does exist, however, a BLUE freshwater crawfish that is also known as a freshwater lobster.  This may take some searching to find.  Marina

"Craw Dads" Dear Bob, After our emails earlier today I searched the net for info re crayfish. Correct me if I am wrong, but not too many people have an interest in these creatures.  <Not that many... surprising for how many species, interesting biology...> I have spent more than a couple of hours searching and other than recipes on how to prepare them, I have come up with three articles. I live in Canada and to see these creatures is a relative rarity. I suppose elsewhere, i.e. the U.S. and Australia, they are considered too common to get excited about. I did live in Mississippi in the early 80's and do recall them on menus, ( I did not partake) but still kind of think of them as an unique creature worthy of observing. Here at home, my favorite creature (outdoors) is our toads, we have an extensive garden and pond area dedicated to just those creatures. Just because I don't know, where abouts in the U.S. do you reside? <In southern California, next to Mexico, a town called San Diego> Do you ever come north to Canada? <Yes, but not often... usually travel to places where the water is warmer... to dive, make photographs. Bob Fenner> Linda

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>

Ditch Bugs Hello guys and thank you for taking time to read this Recently I caught some crawfish to cook at home... I kind of felt bad so I took the two smallest ones "about three inches long" and put them into my freshwater tank "75 gallon" with the rest of my fish....two Bala shark one red tail shark a striped cat and bushy nose Pleco.  to protect my fish I removed the part of their main claw or pinchers that moves to pinch. <Youch!  I am not familiar with that practice.> my question is what effect can the craw fish have on my tank. i.e......cleanliness and stress on the fish... or how do they breathe and what do they eat?  or if I should just take them out?  thank you for your time!!! <I have 4 crawfish in one of my sumps, they are more entertaining than the fish in the main tank, they will eat just about anything, I feed mine algae wafers and whatever leftover pellets or frozen food I have sitting around at feeding time.  I doubt your fish are in too much danger, in fact, if your catfish gets big enough, your crawfish may be in danger.  They are good scavengers, I'd keep them.  Best Regards, Gage>  

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