Please visit our Sponsors
Crayfish, Crawdads, Yabbies, Ditch Bugs Environmental Disease

FAQs on Crayfish Disease: Crayfish Disease 1, Crayfish Health 2, Crayfish Health 3, Crayfish Health 4, Crayfish Health 5, Crayfish Health ,
FAQs on Crayfish Disease by Category: Diagnosis, Nutritional, Trauma, Infectious, Parasitic, Social,

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 Selection, Crayfish Systems, Crayfish Feeding, Crayfish Reproduction, Freshwater Invertebrates/Use in Aquariums, Freshwater Crustaceans for the Aquarium, FW Crustaceans 2, Fresh to Brackish Water Crabs, Hermit Crabs,

Hi I need help with my crayfish       2/17/20
I did a water change and had them in a tank together just yesterday and added some plants in where the plants started having some plant juice out
and killed 2 of my crayfish now one of my female crayfish abdomen is slowly turning white and her claws and legs are falling out... What is happening?
<Reads as some sort of overt poisoning. I would MOVE your crays NOW to somewhere (established) else; or barring this, change out most of the water, add some activated carbon to the filter, and REMOVE the plants if you haven't already. Bob Fenner>

Crayfish position      1/25/18
Like to seek your help.
Is it weird that my crayfish is often in this position?
<Could be; yes... many species need to get out of the water at times, and they can't live in their own wastes>

There's no filter. He had shifted the mini stones and kinda stacked it higher so he can be in a more "comfortable" position .
<Need a filter>

The big stone was for him to climb.. instead he used it as a hiding corner.
<And a larger world... Please read here:
and the linked files at the bottom. Bob Fenner>

Re: Crayfish position   1/26/18
Thank you for the prompt reply.
I also do on the air con in my room at night. About 24degree Celsius. Is that fine for him?
<Should be... again, a larger system, with a filter is what is needed. More stable. BobF>

Weird crayfish behaviorism? Not weird.    /RMF  9/9/16      9/9/16
Hello WWM,
<Hey Darren>
I've recently just bought a Procambarus Clarkii Ghost crayfish and I noticed something weird.
<Was just talking this AM re experiments I did w/ this LA Cray many years back>
So I've had him in this travel tank for 2 days. The tank is about 30 to 40 cm in length and 20 in width and height.
<Mmm; needs more room than this... for stability and more>

This tank was perfectly fine for my previous crayfish which went missing. Its a travel tank of sorts just that it is larger than the usual. I've kept all the water conditions the same as for the previous crayfish which thrived for 2 years. Except that this time I took a step further to ensure that this 90 buck fella doesn't die by adding chlorine remover. Do note that I don't have a filter but I change the tank's water once every week or so.
<Let me ask you to read here re suitable env
.:  http://www.wetwebmedia.com/ca/volume_1/cav1i4/crayfish/crayfish.htm
and here: http://www.wetwebmedia.com/fwsubwebindex/crayfishsysfaqs.htm 
The surrounding and water temperature is pretty high because I put my tank next to a window where sunlight can shine and warm the water up in the day. I live in Singapore too btw so it is pretty warm here. I also fed it bread and some raw
chicken yesterday and I found it to be eating well.
<Yikes... not what I'd recommend. Please search, read on WWM re Crayfish Foods/Feeding>
HOWEVER, there's a problem, it likes to climb onto the top of my fake plant, and lay sideways there with half of his body out of the water. Why is he doing that and is it something I possibly have to worry about?
<Trying to escape... which they do... But there may well be an issue with water quality here. Please do the reading, and write back if all is not clear about how to proceed. Bob Fenner>
Weird crayfish behaviourism?      /Neale       9/10/16

Hello WWM,
I've recently just bought a Procambarus Clarkii Ghost crayfish and I noticed something weird.
So I've had him in this travel tank for 2 days. The tank is about 30 to 40 cm in length and 20 in width and height.
<So, 16 litres/4 US gallons. A bit small for long-term success.>

This tank was perfectly fine for my previous crayfish which went missing.
Its a travel tank of sorts just that it is larger than the usual. I've kept all the water conditions the same as for the previous crayfish which thrived for 2 years.
Except that this time I took a step further to ensure that this 90 buck fella doesn't die by adding chlorine remover.
<If you're spending 90 US dollars, you should definitely be investing in a bigger tank! Otherwise this is like buying a racehorse but keeping it in the bathroom...>
Do note that I don't have a filter but I change the tank's water once every week or so.
<Again, why not spend the money on a filter? An air-powered sponge or box filter will cost very little, and an internal canister filter little more. Both will do the trick, and protect your investment -- not to mention make your pet happier.>
The surrounding and water temperature is pretty high because I put my tank next to a window where sunlight can shine and warm the water up in the day.
I live in Singapore too btw so it is pretty warm here.
<Your Crayfish will be happy at room temperature in Singapore; around 20-22 C is ideal for this species, given its subtropical US distribution. No need to "boil" it! Indeed, very warm conditions will stress your crayfish.>
I also fed it bread and some raw chicken yesterday and I found it to be eating well.
<Neither of these foods is appropriate. Instead, a range of kitchen leftovers will be much better. Some fresh greens (lettuce, cucumber, cooked peas) alongside small quantities of seafood and white fish fillet, either raw or cooked. Very occasional offerings of rice can be given. Raw chicken is a bad idea because of the risk of disease, both to you and your crayfish. Aquaria "culture" Salmonella very easily, leading to nasty food poisoning in humans. And raw chicken often has Salmonella bacteria. So dropping pieces of this in an aquarium is just asking for trouble!
Occasional cooked chicken might be okay, but maybe once every month, no more often than that. Instead you want to focus on calcium-rich foods for the shell, so unshelled prawns are good. You can buy small dried fish in Asian food markets which are very useful too, because they contain tiny bones the crayfish will consume. Also, an iodine source; Sushi Nori is good, but any other seaweed should do too.>
HOWEVER, there's a problem, it likes to climb onto the top of my fake plant, and lay sideways there with half of his body out of the water. Why is he doing that and is it something I possibly have to worry about?
<Crayfish will leave the water when heat-stressed or exposed to low oxygen levels in the water. Review, and act accordingly. Cheers, Neale.>

Crayfish iodine        4/4/16
I got a Orange Mexican Dwarf crayfish recently. He molted once. Eating well. Looking good. Cycling process isn't complete, but frequent water changes are done.
<Mmm.... you should (have waited).... and do what you can now to cycle this system. Read here Re
The presence of ammonia, nitrite... is debilitating; weakening>
I saw in wwm that iodine is very essential for them. Would it be okay to use iodized salt?
<Mmm; not really. Very little useful iodine in such>

It's alone in a tank. I know it's deadly for other fish.
<Actually; no.... Iodine IS a halogen; an element in a family of toxic elements; but in some valence stages it is an essential element... for us, fishes; crustaceans>
But there are no other fishes in my case.
Thought I'd rather confirm it before taking blind risks, because it's a lovely pet. Haven't found any thread on it in wwm or elsewhere.
<A good question, but I'd use a commercial preparation of iodide-iodate...  You can buy one online or at a fish store... made mostly for saltwater systems. E.g.: http://www.seachem.com/reef-iodide.php>
Thanks a lot!
- Matthews
<No test kit necessary; just add a dose when you do water changes... weekly. Bob Fenner>
Re Orange dwarf Mexican crayfish coming to surface to breathe         4/5/16

I had kept him initially in a bowl (first pet), and I noticed it coming to the surface to breathe. I read that it is to get additional oxygen from the air. So I kept rocks by could reach the surface.
<Mmm; needs a filtered setting... I see below that you're aware>
I started doing research on them only after buying, and understood bowls are bad, and about the nitrogen cycle. So quickly got a small tank and filters. But the filter is a little too strong for the tank. And it's quite difficult for Cray to reach the surface and sit peacefully and breathe.
<? Shouldn't "need" to reach the surface>
So will it drown if it doesn't come to the surface?

Because the filter is pretty good, and oxygen supply shouldn't be a problem. Right?
Or should I make quick readjustments and reduce water level or something?
And I came to know about the nitrogen cycle a little too late (after buying. Too ignorant). I'm doing 20% water changes every week. Is there anything I could to help him through the cycle?
<.... did you read where I referred you? Do so>
And food? I give it half of a shelled pea, or a small piece of carrot usually. I tried sinking pellets, which it loves a lot more than the carrot. The pet store people said it loves live or dead fish, and even insects. Could it carry diseases?
<.... and search, read on WWM re Crayfishes.
I'm a little worried about the water quality of overfeeding, with larger food stuff, because he takes them into his cave and stashes them (possibly)
Thanks a lot!
- Matthews
Re: Orange dwarf Mexican crayfish coming to surface to breathe         4/5/16

Thanks a lot for the quick replies!
And a small private question. What do you do for a living?
<Mmm; well; folks mean at least two things by "a living"... I pay my bills through previous investments; mainly real estate and stocks/bonds; to a lesser degree from royalties on books, photo work, and patents. What means life to me that also pays is I am a content provider (sell writing, images...) in the petfish and dive/adventure genres. >
And for how many years have you been in this field?? ��
<A very long time; more than fifty years. Oh, my bio. here:
Bob Fenner>
Re: Orange dwarf Mexican crayfish coming to surface to breathe         4/5/16

Wow. 50 years? That's really cool!
<Ah yes; a good long while. Other than a few years (also) teaching H.S. sciences, have spent my entire life in the ornamental aquatics field>
By the way, your articles are great! So is the website as a whole!
Great work!
<Thank you for your kind, encouraging words Matt. BobF>

Jerusalem crayfish.... 25 megs....       9/29/15
Your email has been deleted due to too-large file size.... re-size (hundreds of Kbytes) and re-send. B
Jerusalem crayfish... 5.5 megs.... Disease issue, commercial culture       9/29/15

Long time I was engaged in cultivation of crayfish Cherax quadricarinatus - red claw. Recently I decided to open a farm and I ordered brood stock from Indonesia, and they die since then - the supplier has no mortality.
From the moment of arrival about each day dying 5 to 10 pc.s.
<Do review water quality... the documentation you sent implies ammonia 0.73 mg/l, and nitrite 0.24 mg/l; both these are toxic at these levels. My guess would be insufficient filtration, overstocking, or under filtering. Perhaps a combination.>
My crayfish that are in the same room are a live and eating.1. I tried to an antibiotic2. I raised the content of salt in water.3. According to the recommendation of the central laboratory of the ministry of agricultural did Formalin twice - After secondary check in laboratory reported that procedure work well, but there was one bacterium which couldn't be designated.
<See above. Bacterial infection is unlikely the immediate cause of death. Water quality is the problem.>
For prevention recommended BROMEX 50 – as far as I know it anti Crustaceans, that the reason why I didn't do it yet. In Israel I have nobody to ask about crayfish and I couldn't find the veterinarian with experience on Crustaceans.
<Presumably not much farmed for food... not kosher.>
Attaching photos and laboratory test. Please help to understand what kills my crayfish, and how to cure it – on your recommendation I will make additional tests. Accordiпg to recommendations in your articles I already added reef iodide of Seachem . Laboratory test indicate Temnocephala stable to all treatments that i have done With best regards, Slava
<Hope this helps, Neale.>

White Lobster/Red Spots   12/27/12
Hello, I have a white lobster (crawfish) I have had him for about 3 months.
I had him in my African Cichlid tank since bought him.  I noticed he has gotten red spots on him. Like the ends of his claws eye guards and the bumps on his shell.  I thought it may have been because the pH in the cichlid tank is at 8.0 so I thought it was to high for him.  I moved him to my fry tank and he hasn't changed. He has not molted yet since I have had him.  I tried to rub the red off but it's not coming off.  Have you ever heard of this?  I can send you a picture to better explain if you want. 
Thanks, John
<Hello John. This does sound like the shell is eroding, i.e., losing minerals. These can be because the water is too soft but also because moulting has been delayed, typically a problem caused by insufficient iodine in the diet. Let's review. Crayfish need moderately to very hard water with a high degree of alkalinity, so first of all check the carbonate hardness, which should not be less than, say, 7 degrees KH (general hardness, degrees dH, is less important but should be fairly high as well, preferably 10 degrees dH). Now, what sources of calcium are you providing?
Things like whole fish with bones in (e.g., lancefish) and unshelled invertebrates (e.g., krill) are good. And how are you ensuring iodine levels are sufficiently high? What iodine supplements are you using? Marine aquarium iodine drops at 50% the quoted dose work well. Cheers, Neale.>
Re: White Lobster/Red Spots 12/27/12

Thank you for your fast response and providing me some insight to getting him healthy again.  I'm heading to the pet store today and get some iodine drops and a hardness tester.  All I have been feeding him is shrimp pellets and algae wafers I didn't even think about his calcium needs.  Thank you for your response.  John
<Most welcome. Do read these articles while you're on the site:
Cheers, Neale.>

Health Concerns with Blue Crayfish    4/20/12
Five weeks ago we purchased a blue crayfish from a local fish shop. We don't know how old she is, but she is about 4" long. She lives by herself in a 20 gallon tall aquarium with four artificial plants of varying size, a thick layer of artificial (blue and white) gravel - which we are hoping to switch out for natural stone gravel in the future, and a large piece of slate rock that is propped up by a smaller piece of slate to fashion a cave for her to hide in. Her tank also has a hanging submersible heater which keeps her water around 71-72°, a Top Fin filter system, and a pump with wall bubbler for aeration. We do not have any other fish or live plants or animals in the tank. Her diet consists of frozen peas, crab & lobster sinking pellets, algae rounds, and frozen bloodworms. Her water is about 3/4 RO water with 1/4 tap water.
<Why the RO? What aspect/s of your source/tap water are you trying to dilute?>

 We added the standard amount of tap water dechlorinator prescribed on the bottle and have switched out her filter's media cartridge twice since we've had her because the color on the gravel keeps flaking off and clouding the filter, which is why we want to replace the artificial gravel with natural stone gravel.
We are new to owning a blue crayfish and, because of a lack of research and understanding on our part, we did not know about the fishless cycling of a tank before introducing a fish into it. We had already purchased our blue crayfish. So we bought an API Fresh Water Master Liquid Test kit and have been testing the water for pH, ammonia, nitrite, and nitrate every other day. It took over four weeks for the tank to cycle. Not wanting to speed along the cycling process with any kind of BioBoost product, we used the prescribed dosage of SeaChem Prime to help detoxify the ammonia and nitrite while the ammonia spiked (up to about 1.0 for a week), and the nitrite spiked (up to about 5.0 for nearly two-and-a-half weeks).
<Both VERY toxic>

It was awful - our Cray hid in her cave the entire time, hardly ate, and spent her days and nights digging and rearranging her gravel beneath the rock. Every now and then she would come out to visit and stretch against the tank walls, but she wasn't being active outside the cave and she clearly wasn't happy about it, understandably. We think the only reason she made it through the cycle alive was because of the SeaChem Prime.
We are now at these levels: pH - 7.6, ammonia - 0, nitrite - 0, and nitrates - 10.
About a week or so ago I added a few drops of liquid iodide to her tank as well to help her in case she was molting.
I don't know if we should be adding iodide to help her molt, or calcium to strengthen her shell, as it kind of seems like crayfish need both. Do you have a recommendation of what to use and when?
<Yes... posted on our site. Read here: http://www.wetwebmedia.com/FWSubWebIndex/crayfishdisfaq.htm
and the linked files above>
Over the past few weeks we've noticed some odd discoloration on her. She was a nice bright blue when we got her. Now she has some red on the lower edges of her tail and bottom of her thorax. It's a gradual fade from blue to red, not patchy red blotches. We've also noticed that she now has visible dark brown lines on her abdomen, specifically in between the little segments of her tail when she curls it under her.
<I see this... troublesome... Perhaps a sort of chemical burn from the prior ammonia, nitrite exposure... Might be due to a nutritional deficiency>
We've read that crayfish discoloration can be caused by a number of factors including stress, dirty water, poor water conditions, and molting.
<Ah yes>
Because of the tank cycling we know that she's likely been stressed and dealing with poor water conditions for the past month. Luckily, they are back to normal now. Do you think that this could be the cause of her red and brown discoloration?
If so, how long do you think it will take for her coloration to return to normal?
<Next molt, two...>
Or could this be a sign she is due for a molt? We are not so worried about the red coloration, but the brown coloration between her tail segments concerns us.
Also, we were advised by a local fish store not to do any water changes while the tank was undergoing its first cycle.
<See WWM re... I would do such changes if NH3, NO2 exceeded 1.0 ppm, stop feeding.>
 However the water was getting dirty from food she was not eating when her appetite decreased, and when her ammonia and nitrite levels were at their peak we did a few 20% water changes with gravel vacuuming.
 But not much beyond that because we wanted to wait for her water conditions to level out before we started a pattern of bi-weekly of 25% water changes with gravel vacuum. So I suppose it is possible that her water could be fairly dirty (and it is when we stir up her gravel), although it looks pretty clear when it all settles, with the exception of the gravel color flaking off. But now that her tank has cycled we want to start changing her water and vacuuming her gravel more often. How often and how much can we clean her gravel without risking jump starting another cycle?
<Now, no worries>
She also has a large rust-colored spot on the top of her shell near her head. It appeared about three weeks ago and has not really shrank or changed any since then. It has grown some. It doesn't appear to bother her.
We thought it was caused by her slate cave. She relocates her gravel frequently, builds it up, then leaves herself no room to crawl out of the cave. When she tries to crawl out, since it is the highest point on her body, it scrapes against the top of the rock. We've been assuming that the scraping is what caused the rust-colored spot.
<Mmm, doubtful>
 We noticed it after she'd blocked herself in for the first time and was scrapping again the rock to try to get out of the cave. This happened just before the ammonia spike, about a week after we first got her. But then I recently learned of shell rot - and that it if often caused by poor water conditions and leftover food in the gravel - both of which were a problem for us, and became concerned that perhaps that is what the rust-mark is or that maybe that's what the brown on her tail is.
Do you think this is shell rot or just a scrapped shell from the rock?
<Stress overall>
How can we identify shell rot? Is there a treatment you'd suggest?
<Mmm, none>
 We've read that Melafix is a common treatment
<Is garbage... may alter nitrification>
(but isn't very effective) and that salt dips or adding a small amount of salt to her tank are the preferred treatment and are our best bet. We spoke to someone at the local fish shop who recommended that we just add a bit of salt to her tank and NOT vacuum her gravel, change her water, change her gravel, or give her a salt dip until she shows signs of improvement because if she's already sick the stress of these changes could do more harm than good.
Finally, she also has one little leg in the back with pinchers that are stuck open. There is a small red spot right in the joint and she picks at it and scratches at it. Do you have any idea what that might be?
<Again... the same causes>
Since her water has stabilized, she's started eating more (though less than she did at first - now she eats about every other day), but she remains fairly active, constantly moving her swimmerets, always rearranging her gravel, and occasionally coming out for a stretch or quick walk around the cave.
We are just, obviously, very concerned about the discoloration, possible shell rot, and any potential long-term damage from the water cycling. Since we are new crayfish owners we don't know if this is a sign of molting, a temporary repercussion of the poor water conditions during cycling, or if there is something more serious going on here (and if so, how to treat it).
What would you recommend we do?
<Read... I would have use Dr. Tim's One and Only or the Fritz or other bacteria "starter culture", but now it's too late>
The first two photos are her when we first got her. The second two are her
Any help you can provide us would be extremely welcome and appreciated.
Thank you!
<Do write back after reading if you have further questions, concerns. Bob Fenner>

Re: Health Concerns with Blue Crayfish    4/21/12
Hi Bob,
Thanks so much for your reply back. The RO water we are using is to dilute the high level of pH in our tap water (about an 8 normally). With the RO the tank water is around a 7.6.
<Mmm, for this species of Crayfish either is fine>
We have some new developments with our blue crayfish. Last night she was scratching under her tail a lot, but she came out for a few laps around the tank. As I mentioned in my prior email, her appetite has decreased, she's stayed mostly hidden in her cave for the past month, she's been rearranging her gravel endlessly, and we noticed black discoloration on her tail. We've attributed her odd change in coloration, lack of appetite, and hiding to the rough first cycle she survived though. She seemed to be feeling okay when we left for work this morning, and ate about half of an algae round.
<Ah good>
Tonight we came home from work and found her laying on her side in the cave with her tail curled up completely under her. She seemed very very uncomfortable and the situation looked grave. Then she started shifting and we noticed a whole lot of black under her tail. Upon further examination and lots of reading online, we've discovered she has tons of tiny little black eggs! All we can think is that she must have been pregnant when we got her, but we had no idea.
<Mmm, not pregnant... these eggs are not fertilized>
The more reading we did, the more others commented that their blue Crays hid all the time, dug the gravel a lot and lost their appetite before laying eggs...so it all kind of makes sense now.
Also, the black on her tail makes sense now too.
Now, of course, we have a whole new world of questions.
1. She looks SO uncomfortable. For the past several hours since we got home, her tail has been tightly curled up under her, holding the eggs. She lays on her side, then moves and tries to get comfortable, then shifts again, and keeps switching sides that she lays on, but she really doesn't move or walk much, just enough to try to flip sides and get comfortable.
She just looks extremely uncomfortable and keeps laying on her side. In all the other pictures we've seen online of other blue crayfish with eggs, they are all standing up and look almost normal. Is it normal for her to lay on her side and look so miserable while laying eggs? How long can we expect this to last?
<Not normal to lay on side... don't know how long the behavior will continue>
2. How long will these eggs stay with her under her tail?
<See/read where you were referred to... days to a week or so>
Will she drop them on the tank floor and let them hatch there, or will she hold onto them under her tail until they hatch? If so, how long until they hatch? Will she seem so miserable the whole time it takes them to hatch?
<They won't hatch... this is a dioecious species... takes two to tango>
3. Is there anything we can or should be doing for her right now? We're weary to do anything - change her water, vacuum the gravel, turn on her tank light, feed her, etc. - because we don't want to stress her out right now.
4. We read that most babies don't make it. I think the black color means they're fertilized, but again, we're so new to this that we really have no idea. It's all a complete shock to us since we were honestly convinced she was dying after that awful cycle and strange discoloration. What do we do with the babies? We can't keep them all (assuming any of them make it) because we only have a 20 gallon tank and simply don't have room for them all, but should we take them to the local fish shop to sell or remove them from her tank once they hatch?
<The stress from being put through cycling, the nitrogenous waste exposure prompted the egg production... close to death experience... Perhaps closer>
Again, any help or additional advice as to what we can do for her would be
appreciated. Thanks!
<Welcome. BobF>

Yabby's tail curl up, toxic water cond.s     3/14/12
Hi there,
Here I am asking for your help again. Missy (my female Yabby pet) has her tail curled up to her body in the last two days. She held it like that all the time, which is abnormal. Before she only did it when she needs to run or claim a rock. Is that a sign of sickness?
<Mmm, maybe... perhaps a dietary shortage, water quality or reproductive behavior>
She is the only one in the 2" tank. I change water change 25% every week.
Ph is at 8 and 2 drops of iodine every time I change water.
The tank however is going through a biological cycle with ammonia = 0.25,
nitrite = 5
<Even more so!>

and nitrate = 10. Tested last week. The reason I did not test this week is because through internet reading, it seems best for the tank to go through the cycle naturally, without adding any chemical liquid.
So if there is nothing I could do about it, there is no point to test the water. But the question is am I right? Should I buy the Stress Zyme to speed up the cycle?
<It won't do this... stop feeding for now and read here:
and the linked files above. Bob Fenner>
Thanks so much for your time and help.
Best regards,

I need help with my crustacean 1/5/12
Good morning,
<And you>
The pet store just called my crustacean an orange lobster, so I'm not sure specifically what type he is.
<Mmm, likely a Procambarus sp.... a species of Crayfish>
I bought him four months ago, he is in a ten gallon tank with live plants, rocks, feeder fish,
<A very poor idea to add/use... nutritionally and in terms of disease transference>
and a dwarf gourami. The tank has a filter and heater with the temperature between 75-78 degrees.
<Too high for this temperate lobster. Please read here:
and the linked files at the bottom on Crays>
This is my first lobster and I'm afraid he may be dying. I haven't added any iodine to the water nor have I checked the water, I've just done routine water changes every week. The people at the pet store didn't tell me I needed to do these things, they just said he needed a ten gallon tank with rocks and a filter and as for feeding they said he will eat anything.
<Mmm, no>
I have been feeding him sinking pellets, blood worms, and I just recently added the feeder fish. I read in another article that the feeders sometimes carry disease, so I'm afraid he might have caught it.
<They do, but not likely for the lobster... The gourami though, yes>
I found him this morning on his back and only his tail and swimmerets were moving. I moved him from the tank to a separate container and he wouldn't move, only5 his swimmerets. Even when I touched him, he didn't move. I put a food pellet in with him as well and he did not eat it.
He has been in there for hours now and he is still not moving anything else but his swimmerets. I'm not sure if this was because of the feeder fish, because he only ate one of them, or if it was because I didn't add the weekly dose of iodine. It doesn't appear that he was trying to molt either. Is there anything I can do to help him?
<Yes... read where you've been referred. You need to lower the water temperature, to the low 70's, even room temperature, and find out re your water quality. All this is gone over where I've asked you to read>
I have been searching online all day and have found nothing.
Thank you,
Jessica Sikorski
<And Jess, do write back if you're still not clear re what course of action you plan. Cheers, Bob Fenner>

Cherax tenuimanus listless and not eating - no it's not moulting, env. 11/24/10
Hi WetWebMedia,
History: I have a blue (well it used to be) marron (Cherax tenuimanus) that is approx 2years old weighing around 50g. I got it from a marron farmer whilst doing experiments during my honours year at university (the thesis was on marron nutrition).
Problem: The marron has not eaten for 3-4 weeks, it is listless, doesn't lift it's claws in response to my presence, doesn't get 'excited' when food is introduced into the aquarium. Has small brown patch on each of it's claws.
Water parameters: Ammonia - 0.0, Nitrite - 0.0, Nitrate - 0.25ppm, temp - 23-25 degrees Celsius, pH - 8.4
Water changes: 50% once weekly, gravel vacced
Additives: I add bicarbonate soda (1 tablespoon per 24L), triple does Wardley's dechlorinate (we have high levels of chlorine in our tap water and there is also Chloramine), rock salt at 1 tablespoon per 24L, Easy-Life fluid filter medium (10ml per 30L). I have read on WetWebMedia that iodine needs to be added to crayfish tanks so I am getting SeaChem iodide as well.
I will not put rock salt into the aquarium once I start adding the SeaChem product.
Food: Crayfish (Cherax spp.) formulated food, zucchini (blanched), sinking fish pellets (treat once weekly), algae chips, lettuce, kelp paper (used for making sushi wraps).
Filter: No filter, just aeration.
Tanks size: 24L
Thanking you in advance for your help!!! Please let me know if you require further information.
<Hello Philippa. The problem here is that this crayfish is being kept in a tank that is too small and not properly filtered. I'm writing this as someone trained as a zoologist and who spent years ferreting about university aquaria and labs as an undergraduate. I've visited many zoology departments over the years, and by and large, the way animals are maintained in labs is very variable. Despite laws ensuring good welfare with regard to mammals and other vertebrates, invertebrates tend to be treated much more poorly, and even fish and frogs commonly suffer from neglect of all types. I won't name names, but I've been to world-class universities and walked away in a state of shock after seeing how some of the animals were maintained. This is especially the case with the "expendable" animals given to undergraduates and masters students. I'm about as pro-science as anyone on the planet, and flaunt my PhD with pride, but a lot of zoologists have not the least idea how to properly maintain "lower" animals in the long term. What I'm getting at here is that the way your crayfish was maintained at the lab should not be taken as the model for maintenance at home. Quite the reverse in fact! The problem with invertebrates generally is that we know next to nothing about their healthcare. Essentially they exist in a binary state: happy and healthy, or sick and dying. Medicating them just isn't an option in most cases. So you need to provide tip-top conditions right from the start. Because crayfish are extremely hardy animals, they take a long time to sicken -- and yours is clearly sick -- but on the other hand when returned to good conditions there's a very good chance your crayfish will recover. So let's start from the top. A crayfish the size of Cherax tenuimanus needs a fair amount of room. I'd say 20 gallons/75 litres, and certainly not much below 15 gal/55 l. Heating may or may not be required depending on your ambient room temperature. But filtration is essential. As I'm sure you realise, Cherax tenuimanus is losing out to Cherax cainii because of its lesser tolerance for poor environmental conditions, including stagnant water. So you're definitely after a brisk water current, lots of oxygen, and clear, neutral, moderately hard water chemistry. If there's no filtration I just don't believe you have zero ammonia and zero nitrite all the time, and 0.25 mg/l nitrate is so trivially low and outside the range of aquarium nitrate test kits, I don't believe that result either. Be sure you're using your test kits properly. Most tap water has a nitrate level around 0-50 mg/l, and in cities especially nitrate levels below 30 mg/l are very unusual. Given this range, aquarium nitrate test kits tend to detect amounts from 0 to 100 mg/l, with five or so steps between those extremes. Salt isn't essential as such, but I would use a proper Rift Valley salt mix if you have hard water, like the one described at the link below, though perhaps at half the recommended dosage. Bicarbonate of soda raises carbonate hardness but not general hardness.
I hope this helps. Cheers, Neale.>

well, well, and sick Chompy

my blue yabbie... hlth./env. - 6/12/10
Hi I have a blue yabbie, I live in Australia. It has developed a large brown spot and lost both his claws. He used to be so active and has been in hiding for about two months, he has lost his appetite and does not seem to want to eat. He used to be so active , he is in a 20 litre tank and he is the only yabbie in there as he ate all the fish . He used to be really aggressive and it seems like he now has depression and is in permanent hiding. Can you please tell me what might be wrong
<Hello Veronica. It's almost certainly poor environmental conditions that are to blame. 20 litres isn't enough space for anything but the smallest crayfish, so if your chap has a body length above, say, 5 cm, he really needs a bigger home. Filtration is essential, not optional, and diet should be based primarily on green foods, not fish. Do read about the needs of these animals, and pay attention to water quality, water chemistry and the use of iodine supplements.
Cheers, Neale.>

Question concerning Crayfish. -- 06/15/09
Hello there, names Josh. I've been searching the internet for a while now and have yet to come across the information that I am after.
Though your site is quite informative and I've picked up a few bits of info that will help.
Right so I'll fill you in with a bit of background info first: I've had the tank for about 3 months now, it's a 60 litre (15ish gallons?) tank and my first addition to it was 2 crayfish, which I believe are Red Claw crayfish
but im not 100% on that.
<A bit small for Crayfish and fish; do bear in mind Crayfish are opportunistic, and they'll view small fish as potential food.>
Shortly after I added several fish including some different types of tetras, a couple of bronze Corydoras, a Plec (who is growing extremely fast), a male and female fighting fish and recently a couple of guppies.
<None of these are viable in 60 litres. A Plec will need something upwards of 200 litres, Corydoras should be kept in groups of 5+ specimens in tanks 90 litres upwards, and Guppies also need a lot of space, say 90 litres, because the males are very aggressive towards each other and the females. A male Betta is simply Crayfish food, being so slow and easily captured, and in small tanks, male Bettas do tend to harass female Bettas.>
I've lost a few of the tetras and a guppy which im not too bothered about, as when I bought them I expected a few of them to get caught, I guess its good for the crayfish's diet to have some live food available (which has become pretty much impossible to acquire with a lot of new laws coming in in England about live bait....).
<The English laws are about animal cruelty, and sticking animals together and not caring if some of them get eaten is irresponsible, whether or not you personally view it as cruel! These laws don't stop the trade in live
river shrimps, bloodworms and other invertebrates, but yes, most retailers have taken these laws to mean the use of feeder fish is prohibited. It isn't clear that's true in point of fact, though doubtless someone could
make a case and set a precedent. That American hobbyists use feeder fish isn't an advantage; Bob has long argued that feeder fish are a major cause of mortality to things like Lionfish, and recent work on Thiaminase has clearly demonstrated that Goldfish and Minnows are highly inappropriate foods for predatory fish. So unless you're breeding and gut-loading your own livebearers or killifish, there's no safe way to use feeder fish, and moreover, most predatory fish don't need them anyway. Besides, crayfish are largely herbivores/detritivores anyway, so there's no need to give them live fish as food. Algae wafers or their equivalents make excellent staples, augmented with occasional offerings of meaty foods such as small
pieces of krill and lancefish now and again. Do see here:
The crayfish are around 4-5" now and are about to moult again. Their diet includes sinking pellets named "Crab Cuisine", flakes of fish food that the fish don't get, live plants, and frozen food such as brine shrimp and bloodworm.
Okay so here's my query: Since I've bought them I've been noticing that they have these strange white worms on them, they are usually around the front of their face, near the eyes and the shorter antennae/feeler things they have.
<Harmless commensals.>
But they do move around the body as well... At first i thought they might be somewhat beneficial to the crayfish cleaning them and stuff but I thought it best to check as when I was searching the internet I came across an un-answered question where someone's crayfish was found dead with "loads of white worm things crawling out of it".
<Not a threat as such.>
Also I was wondering if you could provide me with or point me in the direction a DETAILED list of food (household vegetables and meats) that the crayfish can eat because I don't want to be putting something in there that will be harmful to them.
<See above, and stop feeding them live fish.>
Thanks a bunch for your time and I'm sorry if you've already answered a similar query and I've overlooked it. :)
<Cheers, Neale.>

Blue Lobster Ill, likely stalled ecdysis/env. issue, reading 4/4/09
I have a ten gallon FW tank with a blue lobster, scientific name unknown.
<... See WWM re>
All water parameters are in normal range with nitrates around 25ppm.
<Too high>

He has been happy and healthy with me for two years although his diet has probably consisted of to
high of a ratio of meat to plant material. Recently, within the past week he has developed a sore on his back that has a white pustule in the middle of it. The area surrounding the pustule is red and is spreading.
The best comparison I could give is a pimple that has come to a head. I tried to remove the white center with tweezers, with no success. At first this growth and redness seemed not to affect him. Now though his appetite is decreasing and he is becoming lethargic.
<... alkalinity? Biomineral content, measure?>
Are you familiar with any parasite or illness that could cause this growth and the accompanying symptoms and or could he simply be reaching the end of his lifespan? Any insight would be appreciated. Thank-you
<... Read here: http://wetwebmedia.com/FWSubWebIndex/crayfishdisfaq.htm
and the linked files above.
Bob Fenner>
Re: Blue Lobster Ill 4/5/09

I am just a little confused. I wrote in hopes of finding some answers for my blue crawfish. He has developed a sore on his back that is growing larger and I wanted to know if anyone has any idea what it could be and if it could be treated. I got an email back informing me to read the disease facts page for this species. However I already scoured these pages. Was this a suggestion that he has crawfish plague, or a bad molt, or a deficiency,
<This... my best guess from the data proffered is that you have a lack of biomineral content>
the sore he has is most definitely not the worms that others have written in about. The white center of the sore is inanimate and I have tried to tweeze it out. However his health is becoming worse and I had hoped for some kind of direction because I found nothing promising in the information already posted. If anyone could let me know if they have seen sores like this before and if it alone could be affecting his health and causing his illness.
<... again, you need tests for Calcium, perhaps Magnesium, overall dKH... Iodine...
"White Spot Disease" Not Ick... more Blue crawfish with no new data... 4/5/09

I have written in a couple of times now trying to discover what is happening to my blue crawfish. I was basically told to read over the facts on the website, which I did but the discovery of this "white spot disease" in invertebrates seems to most closely resemble his condition.
<Is not this... the very name specifies fishes>
I have a final question about the illness that my crawfish is suffering.
I have been researching it on the web and I am wondering if my crawfish could have "white spot disease"
<Assuredly not>
It seems to meet the criteria, based on symptoms. He has what look like a calcium deposit with its shell becoming pink and red especially along the lines where the shell meets. My only hesitation at assuming this is the correct diagnosis is that the lobster has not exhibited symptoms until the last month and I have had it for two years. Could the "white spot disease" remain dormant until some environmental or nutritional deficiency caused the disease to take hold? Finally if this is the diagnosis would euthanasia be the best option so that the lobster doesn't suffer anymore? I would so appreciate a quick response. Thank-you for your time.
<The issue at hand is either a cumulative nutrient deficiency or water quality... B>
Re: FW Lobster Woes... still not reading 4/10/09

I wrote in about a week ago having problems with my blue crawfish. He has developed a red sore along one of the grooves in his back and there seems to be a nucleus to the sore. This center of the wound is white. I tried to remove it with tweezers with no success. Then, today, I noticed the white center has grown some kind of a fungus, a white cottony material is streaming from the wound, about a millimeter tall. The lobster also generally has a more reddish tinge to his shell. He is also lethargic and his appetite isn't what it should be. I read about a disease that affects invertebrates, especially prawns, but crawfish as well. I wrote in that maybe my crawfish is suffering from this disease, which ironically is called "White Spot Disease"
<White Spot Syndrome Virus (WSSV). Since this is a viral disease, there is no cure. Without access to a lab, you can't confirm the disease by sight, because unlike the situation when shrimps are infected, crayfish *do not* develop the tell-tale white spots; they just get ill and die. So for this reason, I doubt this is what your crayfish is suffering from. Much literature on WSSV available via Crayfish farming web sites and books.>
My previous inquiry was not suggesting that the lobster is suffering from the fish disease ich.
<Indeed not.>
I know the lobster doesn't have ich but he could have this other disease, no?
<There's really very little about Crayfish diseases in the hobby literature, and apart from the use of iodine supplements to improve health and moulting, there's nothing much known about treatment. It really all
comes down to optimising water quality, providing the right (vegetable-based) diet, and taking sensible preventative healthcare steps such as the use of marine aquarium iodine drops (at half-dose).>
I am looking for any information you may have.
<Sorry, can't offer very much. The best you can do is hope that following a successful moult, the damaged/infected shell will be left behind. Remove the moult to prevent re-infection, but do offer some equivalent source of calcium, e.g., an unshelled shrimp.>
Or even a link to some kind of specialist that may have more experience or information on crawfish, or on this disease that shares the same name as the legendary fish sickness.
<Google the correct name, as mentioned above.>
Is there any way to treat the crawfish?
<Not aware of any.>
Is there some other diagnosis that is possible. The lobster lives in a ten gallon tank with a couple of guppies.
Ammonia and nitrites 0ppm
Nitrates 15ppm
Ph very low @ 6.0, very acidic
<Ah! Here's one possible issue.
Crayfish (and indeed shelled animals generally) do best in hard water. While they may live in somewhat acidic habitats in the wild, under aquarium conditions problems such as pitting in the shell are common (as they are in the wild, too). Would recommend 10+ degrees dH, 5+ degrees KH, and pH 7.5-8 for Crayfish.>
Temp 66F
<May be too cold for tropical Crayfish species such as those from Australia; check the species you have an act accordingly. Cheers, Neale.>

Electric blue crayfish and a very bad molt 2/25/09 I work at my local pet store and have been allowed to take care of my own row of fish. Each row of fish has its own filter Google us if you like I work at 'That Fish Place' . We have some electric blue crayfish which I had to separate because they were slowly killing each other (2 are alone in there own tanks, the other two are in a larger tank together.). Currently the water quality is a PH of 7.6, Ammonia 0, Nitrite 0, and nitrate is 5. The nitrates were off the scale since I've got them down one of the crayfish molted and now has what looks like feathers on his side. It has been two days and he is very sluggish and still brownish pink. His tank mate molted the next day and is a very improved blue. I am not allowed to treat these tanks just keep up with everyday maintenance. Is there anything I can do for this crayfish other than adding iodine to the water. Also I read this was his gills hanging out so that means he may die doesn't it? When I ask my supervisors I'm told it was just a bad molt or blamed for it and you guys seemed like a great place to find answers. please and thank you for your help. <Hello Deanna. I'm not sure whether a Crayfish can be treated after a bad moult. The best you can do is maintain good conditions, feed it by hand if required, and hope that by its next moult things get put right. Provided it will accept food, you might be lucky. But if it isn't feeding, then the outlook is gloomy. Do have a review of these pieces, and see if you can find any clues in terms of prevention. http://www.wetwebmedia.com/ca/volume_5/volume_5_3/crayfish_basics.htm  http://www.wetwebmedia.com/FWSubWebIndex/crayfishdisfaq.htm  Cheers, Neale.>

Crayfish died :( 5/4/08 Hey guys, I've tried searching but haven't found something that fits my situation. My crayfish died today sometime while I was out (it was mostly rust coloured/brown specs with much deeper red in its claws, about 3". sorry not sure of species). I had it for about 2 months in my 18gal aquarium with little problems i.e.: devouring 2 small angels and chasing everything it could. <Typical> even climbing my plants and freefalling to snap at the fish. I removed it to a smaller 10gal tank by itself and added a few white clouds for entertainment - they are cheap at my LFS and fast enough not to get caught. For the next 2 months almost everyone was happy (some clouds were a bit slow on the learning curve) but last week it began to get lethargic and rarely came out of its home (a small pvc length). It moulted 3 times in the first 2 months <This... is a bit too much ecdysis... telling> but never since changing tanks. <Also> I had an algae problem so over a week i cleaned all the gravel <... how?> which made it more active but as soon as the algae started coming back it stopped eating. I feed it mostly shrimp pellets occasionally a small cube of Tubifex worms goes crazy for these). the other day it looked like it was walking on its claws - pointing straight down tail in the air balancing on its claws. <Interesting...> thought it could be ammonia so i did a 20% water change. today it was upside down in the middle of the tank lifeless. Fish are all fine, reading makes me think I needed Iodine (didn't have any, apparent rookie mistake) but wouldn't it have had problems sooner not almost 5 months down the road? Sorry about the length but I enjoyed keeping my Cray and would like to again, but may opt for some shrimp instead so they can join my larger tank. thanks, Bob <Interesting to speculate, but I believe this animal was lost due to a few circumstances... One, being in a situation that was "unnaturally" warm and protein rich (allowing, driving moulting...), the strain of being moved, too much change in water quality, AND an absence of iron particles to replace its "statocyst"... an orientation organ... Please read here: statocyst of crustaceans in your search tool/s. Bob Fenner>

My freshwater blue crayfish seems to be eating its own antenna? Deficiency syndrome, reading 12/10/07 Dear WWM Crew: <Vilma> Thank you for your research suggestions, I followed them but I still did not find the answer to my question. I have a freshwater blue crayfish in a 10 gallon tank, my brother in law gave it to me for he could no longer house it with his fish species. I've had it for a little over 3 months and it seemed to be doing well until about 3 weeks ago when I started noticing that the long pair of antennas seem to have been shortened. <Good observation> The blue crayfish molted a few days after moving her into her new tank but has not molted ever since. <Also a good clue> Two weeks ago I did research online about crayfish eating their own antenna and all I found was that she might me iodine deficient <This and possibly biomineral, and/or alkalinity> so I added iodized table salt <Mmm, not a good manner to remedy> into the tank but I noticed that her antennas after the iodized salt treatment keep getting shorter. I don't think it's her diet, or water quality. <These are the most likely categories...> I have noticed a gray hue at the end of one of her antenna. Can you please tell me why her antennas keep getting shorter and what I can do about it? Thank you, Vilma Molina <Please go back and read on WWM re Crayfish husbandry, disease, nutrition, systems... Your pet lacks calcium, possibly magnesium... maybe in too high/low a pH/alkaline reserve situation... Some of this/these can be supplied through feeding... all posted. Bob Fenner>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: