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Crayfish, Crawdads, Yabbies, Ditch Bugs Disease/Health 5

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

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,

Crayfish translucent growths        10/7/17
Good day!
<Bonjour!>
I impulse bought a 3" Tangerine crayfish and now I'm scrambling to buy the materials to cycle a 10g long tank but for now I'm keeping her in a small 2.5 gallon tub with a sponge filter until then. She recently molted (But lost some limbs because she had horrible shell rot from the shop) and now its been 13 days i have noticed growths from the stumps of her lost appendages!
<Indeed. These are likely 'benign' Protozoans, bacteria or fungi that grow wherever there's plenty of dead organic material. They're benign in the sense that they're not aggressive pathogens that will make your crayfish sick, but they're still undesirable. An antibacterial and antifungal medication known to be shrimp-safe (such as eSHa 2000) could be used here, alongside optimising environmental conditions. To a great degree this sort of 'fluff' grows on crayfish in tanks that have less than perfect cleanliness. The more gunk for them to feed on, the more the Protozoans and fungus will spread onto your crayfish.>
i don't have a test kit yet so i cant tell the parameters but i do a lot of partial water changes every other day and feed her veggies and sinking pellets.
<Good.>
She's acting so differently now and she's just scared of everything unlike before (maybe its because she also lost her claws).. but i digress, the growths look feathery and have spots in them, attached here is a photo i took of her in an ice cream container while i was cleaning the sand in her tub (there was rotting broccoli pieces hidden so it was stinking to high heaven)
<The photo isn't sharp enough to see exactly what the problem here, but for now, I'd assume the benign fluff described above rather than an aggressive crayfish parasite. Still, if you can get tack-sharp photos, sites like
PetShrimp.com have active forums with numerous experienced crustacean-keepers.>
Thank you for helping, I've added some antifungal meds (no copper) but i just want to help her get better soon.
<Understood. Good luck, Neale.>

Re: Crayfish translucent growths      10/8/2017
Thank you for the reply!!
<Welcome.>
Just adding again but here's another pic of Megatron i took the same day, is this photo better?
<Not really. It's not so much the size of the photo as the fact the bit of interest, the fluff around the legs, is basically a blurry mess with black speckles.>
its got dark spots and it worries me to no end.
<They look like baby crayfish, what with the black spots and all! Cheers, Neale.>

Blue crayfish injury      6/14/17
Hi there, I have a blue crayfish and whilst moving it from the tank for cleaning (I scooped it up in its terracotta cave ) I tried to pick it up... it jumped. ..! I jumped.., dropped the pot and banged it's head!
The injury is about 4weeks old. Is this injury likely to kill it? It looks no worse after these weeks.
<That the animal has survived this long is a good indication that it will persist; and clear this crack with the next moult or two.
You do administer Iodide regularly? I'll list the reading: http://www.wetwebmedia.com/fwsubwebindex/crayfishdisfaq.htm
Bob Fenner>

Re: Blue crayfish injury     6/14/17
Yes, marine iodine, half dose as specified in your previous q&a's. Will it moult again though?
<Yes; if it lives>
It's approximately 3yrs old, I didn't expect it to get any bigger, though I'd be delighted if it did.
<Moulting frequency decreases with age/size, but never stops altogether>
Does the head area moult too?
<Yes>
Is the discoloured fur on its pincers normal or should I attempt to remove it?
<Looks like algae of some sort... this will come off w/ the moult>
Thanks for your swift response
<Welcome. Bob Fenner>
Laura

Hole in the head?!  Crayfish      2/25/17
Hey Crew,
(Disclaimer: It's 2:00 in the morning so this is going to be so very NOT articulate.)
<Oh?>
You guys were awesome helping me before and my crayfish is doing much better. She molted a few weeks after I started giving iodine and while she did not recover her pincer yet, I think she will eventually.
<Agree.>
The soft tissue of her "shoulder" (I know actual terminology I swear I'm just really tired) is coming back so I think once that has recovered, she will start getting the actual claw.
<Precisely. The first few tries though will often seem very odd, like a tiny claw totally out of scale to the adult.>
I was worried the arm wouldn't recover at all so I'm relieved. Another good thing is that her gills are no longer exposed. It could be that the ones that had been exposed were actually lost during the molt, but in any case there aren't any exposed now and she was doing well. It's been a relief.
<Yes.>
She was active and awesome. But just now I saw her from an angle where I saw the top of her head and SHE HAS A HOLE IN HER FREAKING HEAD. Ok it is pretty small, and I will get pictures tomorrow, as well as test the water
etc, but right now I'm freaking out and had to shoot you an email. I worked with fish for years in pet stores (don't judge me for this lol) and have seen "hole in the head" disease in fancy goldfish and stuff but WHAT THE EFF IS IT DOING ON MY CRAYFISH? It wasn't there a week ago for sure, that's the last time I really saw her from that angle.
<Likely harmless. Crayfish have calcareous, non-living exoskeletons. Unlike our skin, the shells aren't capable of healing, so if they crack, dissolve in soft water, or get scratched by something harder, that's it until the next moult. It seems a crummy system to us, but heck, arthropods have been operating this way for something like half a billion years, there are
literally millions of species around, and they form the bedrock of just about every possible ecosystem you can think of. So it works. Check the pH is over 7 (acidic pH will cause "pitting") and offer something calcareous for her to eat (like an unshelled shrimp or some krill) and she can recycle that calcium carbonate into her next skeleton. Do also understand if she hasn't eaten enough calcium carbonate in her diet, her new skeleton will be weaker and more prone to damage.>
Uggghhh I should never have taken this poor creature out of the pond I have doomed her!
<Possibly, but I'm sure she's fine.>
*sob*
Ok I'm going to bed now, I obviously need to. Good night.
-Margie
<And to you! Neale.>

Crayfish, bad molt, and mycobacterium      12/14/16
Hello WWC,
<Close enough>
This is very long because I want to give as much information as possible. I am a college student working on my B.S. in zoology,
<Oh! My undergrad. degree as well>
so this is exactly the kind of thing that interests me and therefore I have collected a lot of information about the circumstances.
<Okay>
I have a 10 gallon freshwater aquarium with the following water conditions... the first test is from 5 days ago, and the second is after I did a water change:
First:
Nitrate <20 ppm
Nitrite 0
GH 200
KH 180
PH 7.8
Temp 64 F
Now the numbers are:
Nitrate <20 ppm
Nitrite 0
GH 150
KH 120
PH 7.6
Temp 64 F
<A bit "older"... still; acceptable values>
In the tank resides one female crayfish of unknown species and two "mosquito fish" (Gambusia affinis). I have had the crayfish since November 2, 2015 when I accidentally caught her from a pond at my school (I was netting some mosquito fish from the pond to put in an aquarium because I'm just weird like that). She was only approximately an inch long at the time, and almost translucent, with tiny little baby pincers. While reading up on crayfish, I found a recipe for a gel-type food that I could adjust to meet her needs. It uses gelatin as a binder, and is frozen after it sets, so I can break off cubes to thaw as needed. I made it with dried Spirulina, dried organic kelp, fresh spinach, fresh zucchini, cooked whole shrimp, and some salmon. It is mostly greens, though, as that seemed most appropriate.
Her diet consists of the gel food, shrimp pellets, algae pellets, fresh greens/cucumber/etc., duckweed, and sometimes frozen brine shrimp. I try to keep it varied.
<Good... I'd add a modicum of iodide-ate to the water weekly as well. Have you read on WWM Re Cray nutrition?>
Now she is approximately 4.5" long, and has molted 10 times since I brought her home. The problem started with the last molt, which was July 15, and continued with one that happened 5 days ago. Before I get to that, however, I want to express my reason for emailing you when you have so many posts already regarding bad molts.
<Ah yes>
I had some mosquito fish fry in my 5.5 gallon aquarium, and on June 5th I noticed one fry had a bent spine. I thought maybe he had been injured or something, and never considered that it could be something contagious. Then there were some other anomalies with the fish in that tank and with the tank conditions, the specifics of which probably don't matter in this context. But at some point I realized there were more than one fry with a bent spine, and finally researched it as a symptom of a larger illness, rather than an injury. I began to come to the horrible hypothesis that my tank somehow had been infected with mycobacterium. It explained many of the abnormalities I had encountered.
<Mmm; well.... This genus of bacteria are about in most all aquatic systems...>
**Since this took some time to figure out, it is very likely that I used some tool (a net or whatever) on both the 10 gallon and the 5.5 gallon tanks after the 5.5 gallon was infected.**
I tried treating the 5.5 gallon with Tetra Lifeguard (it's the only medication I had on hand so I gave it a try), which was ineffective against most of the symptoms I was seeing. The number of fish with spinal deformities was going up, and there were several deaths within a few days of each other, so I began to consider euthanizing them.
<I would; yes>
Before I did, however, on July 15 the crayfish molted and was left with at least three exposed gills on one side. They were completely outside the carapace. I went to my LFS (they have a local reputation as "experts"), freaking out a bit, and the guy was worse than useless. He said he couldn't help me, there was nothing that could be done for either the crayfish or the Gambusia. His actual advice regarding the crayfish was, "just keep checking the water conditions and see if she makes it."
<?!>
I euthanized about 15 fish that day, mostly fry, and treated the healthiest ones with Kanamycin. I completely broke down my 5.5 gallon tank and tossed all the live plants, but didn't know what to do about the crayfish in the 10 gallon. I decided to just go on the assumption that crayfish couldn't contract mycobacterium (if that's even what my fish had, but I didn't test them, so I'm not 100% sure), and that the bad molt was due to lack of iodide, which she only really gets from her diet.
<Again; I'd supplement; weekly, add to the water>
The last few months she was pretty much refusing to eat the gel food any more and would just make a mess with it and then leave it sitting on the bottom of the tank. She stopped eating the stuff she usually enjoyed, like fresh kale, and would almost exclusively eat the shrimp pellets or the flake fish food that I put in for the mosquito fish. I kept meaning to buy aquarium iodide to supplement this, but life happened and I never got to it. I didn't realize how long she went without eating greens until I saw the effects.
When she had the bad molt,
<You are leaving these molts in the system I hope/trust, for this animal to consume>
I tried to be more vigilant about water conditions (though when I tested it at the time, the parameters were actually the same as the first test listed above, they weren't horrible, but I hadn't been cleaning the tank as often as I should have been and I wasn't sure if that contributed or not), and tried to get her to eat more green things. Once again, though, several things happened in my life that made it get pushed aside, and she must not have been getting enough iodide still...
She molted 5 days ago and she almost died this time. I found her lying on her side next to her molted exoskeleton, and she had a number of gills outside the carapace again but more this time, and on both sides. One of her antennae didn't look right, and she was not moving. Her little antennules were twitching, though, so I covered the tank with a dark towel
and kept her in the dark and quiet for about 24 hours before checking on her again. At that point she was still on her side, but another 12 hours later she was upright again and eating her exoskeleton. Now I have been able to see her better and not only are a bunch of gills outside her shell and an antenna bent (and the part after the "bend" is turning white), but one of her claws looks really bad, too. She was holding it funny and after a couple days the "elbow" (for lack of a better word) turned very bright red. The redness has spread along that claw and it also looks a little fuzzy, like food that's been left in the tank too long. She isn't very active, she is barely eating her exoskeleton at all, but she does walk
around a little and she is definitely alive and alert. She looks awful though.
<I'd also add a level teaspoon of baking soda/sodium bicarbonate and a "hardness" stone like those sold for turtles in the trade>
I have ordered marine iodide and I am keeping the tank somewhat dark, so she feels safe and hidden, to minimize stress. I bought gallons of bottled water and I **VERY** carefully gravel vacuumed the dirtiest part of the tank (I didn't clean the whole thing because, again, stress. I didn't go too close to the crayfish herself, I let her feel hidden.) and replaced the water (about 50% of the tank) with Crystal Geyser, instead of using treated tap water. I don't know why, it just seemed safer. Maybe that's just paranoia.
<Dechloraminated tap/mains water should be fine. Bottled isn't better for crayfish>
My concern about getting her through this is, can this be caused by mycobacterium?
<Not "caused" per se... or per accidens: that is, not the immediate, direct cause... But bacteria may be playing a secondary role here>
It affects the skeletons of vertebrates, could it affect the exoskeleton of an invertebrate?? Should I take the exoskeleton out at this point? Is it just making water conditions worse as it breaks down?
<I would leave it in... and do what I've mentioned above. Triple dose the I2 now>
I adore this crayfish. She is a remarkable little creature. Can I do anything for her? Is there some medication that would help her recover?
There are things I know I did wrong and will be making an effort to change, but I don't know enough about invertebrate biology to know exactly what went wrong, especially when there are a number of possible causes. I'm attaching a couple pictures of her current condition so you can see what exactly I'm talking about.
Thank you in advance and let me know if there is more information you need.
-Margie
<Welcome. Bob Fenner; who will place this msg. in Neale Monk's in-box for his separate resp.>
Crayfish, molt, Myco- pics      12/14/16

Hello again,
<Marge>
Sorry I forgot to attach the pictures when I emailed you earlier today. I was up late studying for finals so I'm a bit tired lol.
<No worries>
Forgive the reflections off the glass of the tank. Also, I cropped the pictures to reduce their size, so some may be odd proportions. If there are any included here that look weird, they are included because they show something specific, like the gills outside the carapace (which are hard to see because they blend into the rocks) or the antenna that is sad looking. The redness of the claw is obvious, but also if you look closely you'll see the fuzziness... like it's rotting. All these are from the most recent molt that she had about 5 days ago. The first 2 pictures were taken 2 days after molting, the next one where she is on her side was taken yesterday, and you can see how the redness has spread down the claw. In that one she is next to her shed exoskeleton, so excuse any random extraneous body parts.
Thank you again for all your time.
-Margie
<Can't (of course) discern root cause/s here; but do concur the molt is odd/misshapen... Perhaps something missing (deficiency)... I'd add liquid vitamins/HUFA mix to the water weekly as well as to the food mix (like SeaChem's "Vitality" product). BobF>

Crayfish, bad molt, and mycobacterium   Neale's go       12/15/16
Hello WWC,
<Margie,>
This is very long because I want to give as much information as possible. I am a college student working on my B.S. in zoology, so this is exactly the kind of thing that interests me and therefore I have collected a lot of information about the circumstances.
<Understood.>
I have a 10 gallon freshwater aquarium with the following water conditions... the first test is from 5 days ago, and the second is after I did a water change:
First:
Nitrate <20 ppm
Nitrite 0
GH 200
KH 180
PH 7.8
Temp 64 F
<All sounds fine.>
Now the numbers are:
Nitrate <20 ppm
Nitrite 0
GH 150
KH 120
PH 7.6
Temp 64 F
<No major problems here.>
In the tank resides one female crayfish of unknown species and two "mosquito fish" (Gambusia affinis). I have had the crayfish since November 2, 2015 when I accidentally caught her from a pond at my school (I was netting some mosquito fish from the pond to put in an aquarium because I'm just weird like that). She was only approximately an inch long at the time, and almost translucent, with tiny little baby pincers. While reading up on crayfish, I found a recipe for a gel-type food that I could adjust to meet her needs. It uses gelatin as a binder, and is frozen after it sets, so I
can break off cubes to thaw as needed. I made it with dried Spirulina, dried organic kelp, fresh spinach, fresh zucchini, cooked whole shrimp, and some salmon. It is mostly greens, though, as that seemed most appropriate.
Her diet consists of the gel food, shrimp pellets, algae pellets, fresh greens/cucumber/etc., duckweed, and sometimes frozen brine shrimp. I try to keep it varied.
<Good. This all sounds appropriate. Gambusia are a bit hit and miss in fish tanks, but shouldn't cause any problems with crayfish.>
Now she is approximately 4.5" long, and has molted 10 times since I brought her home. The problem started with the last molt, which was July 15, and continued with one that happened 5 days ago. Before I get to that, however, I want to express my reason for emailing you when you have so many posts already regarding bad molts.
<Indeed! It's impossible to know the real problems, but iodine may be a significant factor. On top of that, other dietary deficiencies are possible, but as you suggest, maximising variety, and biasing towards plant foods, probably helps here. Then there's exposure to heavy metals. While clearly copper for example is toxic to crustaceans above certain levels, the problems caused by lower, non-lethal levels aren't often considered by aquarists, but may be important. There may be other factors too, such as day length or season temperature variations we just don't consider, and again, these may be important with regard to properly synchronising all the different physiological mechanisms involved.>
I had some mosquito fish fry in my 5.5 gallon aquarium, and on June 5th I noticed one fry had a bent spine. I thought maybe he had been injured or something, and never considered that it could be something contagious.
<The odd deformed fry is relatively common among fish. They tend to produce large numbers of offspring, but with little of the "error correction" typical among mammals, where deformed embryos will be eliminated long before birth. I guess it's down to the relative shortness of the pregnancy phase, and the far weaker interaction between the eggs and the mother's blood supply. There are exceptions, the Goodeids for example having the equivalent of a placenta, but your Mosquitofish do little more than carry the eggs and provide oxygen; the fry get most of their energy from a yolk
sac, and relatively little from the maternal blood supply.>
Then there were some other anomalies with the fish in that tank and with the tank conditions, the specifics of which probably don't matter in this context. But at some point I realized there were more than one fry with a bent spine, and finally researched it as a symptom of a larger illness, rather than an injury. I began to come to the horrible hypothesis that my tank somehow had been infected with mycobacterium. It explained many of the abnormalities I had encountered.
<Possibly. But Mycobacteriosis is very difficult to diagnose by visual inspection. It's probably impossible to do so, really. It may also be the case that Mycobacteriosis may well be latent in most tanks, but only becomes a problem under specific conditions where fish are stressed or poisoned. In any event, it's hard to say that's the story here, because things like bent spines and failed moults can easily be explained by environmental stress, genetics, dietary shortcomings, etc.>
**Since this took some time to figure out, it is very likely that I used some tool (a net or whatever) on both the 10 gallon and the 5.5 gallon tanks after the 5.5 gallon was infected.**
<Easily sterilised using dilute bleach followed by thorough rinsing.>
I tried treating the 5.5 gallon with Tetra Lifeguard (it's the only medication I had on hand so I gave it a try), which was ineffective against most of the symptoms I was seeing. The number of fish with spinal deformities was going up, and there were several deaths within a few days of each other, so I began to consider euthanizing them.
<Yikes.>
Before I did, however, on July 15 the crayfish molted and was left with at least three exposed gills on one side. They were completely outside the carapace. I went to my LFS (they have a local reputation as "experts"), freaking out a bit, and the guy was worse than useless. He said he couldn't help me, there was nothing that could be done for either the crayfish or the Gambusia. His actual advice regarding the crayfish was, "just keep checking the water conditions and see if she makes it."
<Would agree somewhat; once crustaceans are sick, it's actually very difficult to heal them. On the upside, if fed and protected, subsequent moults can put right any damage.>
I euthanized about 15 fish that day, mostly fry, and treated the healthiest ones with Kanamycin. I completely broke down my 5.5 gallon tank and tossed all the live plants, but didn't know what to do about the crayfish in the 10 gallon. I decided to just go on the assumption that crayfish couldn't contract mycobacterium (if that's even what my fish had, but I didn't test them, so I'm not 100% sure), and that the bad molt was due to lack of iodide, which she only really gets from her diet.
<I would agree with your analysis here, in the sense Mycobacteria species are unlikely to jump from a fish to a crustacean. That said, I don't know that for sure.>
The last few months she was pretty much refusing to eat the gel food any more and would just make a mess with it and then leave it sitting on the bottom of the tank. She stopped eating the stuff she usually enjoyed, like fresh kale, and would almost exclusively eat the shrimp pellets or the flake fish food that I put in for the mosquito fish. I kept meaning to buy aquarium iodide to supplement this, but life happened and I never got to it. I didn't realize how long she went without eating greens until I saw the effects.
<Understood. Their scavenging behaviour does mislead some folks into seeing them as more carnivorous than they really are. Crayfish are more deposit feeders, and tend to consume a lot of algae and decaying plant material alongside carrion and other scraps of food.>
When she had the bad molt, I tried to be more vigilant about water conditions (though when I tested it at the time, the parameters were actually the same as the first test listed above, they weren't horrible, but I hadn't been cleaning the tank as often as I should have been and I wasn't sure if that contributed or not), and tried to get her to eat more
green things. Once again, though, several things happened in my life that made it get pushed aside, and she must not have been getting enough iodide still...
<I see this from your photo.>
She molted 5 days ago and she almost died this time. I found her lying on her side next to her molted exoskeleton, and she had a number of gills outside the carapace again but more this time, and on both sides. One of her antennae didn't look right, and she was not moving. Her little antennules were twitching, though, so I covered the tank with a dark towel and kept her in the dark and quiet for about 24 hours before checking on her again. At that point she was still on her side, but another 12 hours later she was upright again and eating her exoskeleton. Now I have been able to see her better and not only are a bunch of gills outside her shell and an antenna bent (and the part after the "bend" is turning white), but one of her claws looks really bad, too. She was holding it funny and after a couple days the "elbow" (for lack of a better word) turned very bright red. The redness has spread along that claw and it also looks a little fuzzy, like food that's been left in the tank too long. She isn't very active, she is barely eating her exoskeleton at all, but she does walk around a little and she is definitely alive and alert. She looks awful though.
<Agreed.>
I have ordered marine iodide and I am keeping the tank somewhat dark, so she feels safe and hidden, to minimize stress. I bought gallons of bottled water and I **VERY** carefully gravel vacuumed the dirtiest part of the tank (I didn't clean the whole thing because, again, stress. I didn't go too close to the crayfish herself, I let her feel hidden.) and replaced the water (about 50% of the tank) with Crystal Geyser, instead of using treated tap water. I don't know why, it just seemed safer. Maybe that's just paranoia.
<I would be careful dramatically changing water chemistry. Good water quality is important though, and ideally water that's somewhat hard, to reduce osmotic stress if nothing else, but also to prevent further damage to her skeleton.>
My concern about getting her through this is, can this be caused by mycobacterium?
<No idea, in all honesty.>
It affects the skeletons of vertebrates, could it affect the exoskeleton of an invertebrate?
<Completely different mechanisms of secretion and maintenance, so hard to imagine Mycobacteria could affect them/these similarly.>
Should I take the exoskeleton out at this point? Is it just making water conditions worse as it breaks down?
<Crayfish should have access to previous moults; what we do know about crustaceans generally is that consumption of their moult is often significant, and budgeted into their energy equation, allowing them to recycle nutrients. Without access to the moult, they might 'overspend' on calcium or whatever, and that deficit could be lethal.>
I adore this crayfish. She is a remarkable little creature. Can I do anything for her?
<Optimise water quality; offer tiny bits of food periodically; provide a suitable source of calcium such as a bit of cuttlebone to harden the water and possibly be eaten; optimise diet, to include seaweed-based iodine sources.>
Is there some medication that would help her recover?
<The science just isn't there yet. We know almost nothing about medicating inverts. Far more effort is put into exterminating them, insects especially. We probably wouldn't know much about fish medicines either, were it not for hobbyists keeping them as pets. Only very recently has fish farming been an actual thing big enough to warrant research.>
There are things I know I did wrong and will be making an effort to change, but I don't know enough about invertebrate biology to know exactly what went wrong, especially when there are a number of possible causes. I'm
attaching a couple pictures of her current condition so you can see what exactly I'm talking about.
<Thank you.>
Thank you in advance and let me know if there is more information you need.
-Margie
<Most welcome, Neale.>

Re: Crayfish, bad molt, and mycobacterium      6/20/16
Hello again!
<Margie,>
Thank you so much for all the information. As Neale observed, there is a lot more information available out there about exterminating inverts than saving them, so you guys are a rare and valuable resource.
<Thanks for the kind words.>
Since both responses I got asked about this, yes, I do always leave the exoskeleton in the tank every time she molts so she can "recycle" it. (Got a great picture of her eating her own claw once. It was AWESOME. And it creeped my mom out, too, which was a bonus.)
<Heh!>
The crayfish lost her damaged claw the other day. Not just the part that's exoskeleton, either-- there was a good sized chunk of flesh that came off too. She has a little stump that is still bright red and white, and looks quite bad. She hides 24/7 (making it difficult for me to get a good look at her) and barely moves at all. She doesn't explore, or rearrange her tank, or scavenge for food at all. She hasn't been eating her exoskeleton, or anything else that I know of. I kind of gently nudge her tail sometimes just to see if she is still alive (she is). I'm very concerned.
<Understood. Autotomy, the casting off of damaged/trapped limbs, is within the normal range of things crayfish do. So in theory, if the break is clean, she can/will survive without much trouble. But if the damage extends beyond the natural 'breaks' in their exoskeleton, they can quickly become infected. If she survives a week, that's probably a good sign though.>
I removed from the tank the part of her dead claw that was fleshy, after a couple days, since it was beginning to decompose.
<Absolutely! Leaving empty shells to be eaten is good. Leaving decaying hunks of flesh, that's bad!>
I guess my big question is just... in your opinion(s), do you think she will make it? Obviously you can't predict the future (or can you?? o_0) but in your experience is something like this survivable?
<Yes, if the break is clean. Less likely otherwise.>
Also, how much iodine should I be supplementing? Since I usually see the recommended dose is half whatever the bottle says, but then Bob said triple dose, so does that mean triple the half dose (so 1.5x the dose on the bottle label), or triple what the bottle says?...
<Oh, I'd tend to go half the dosage stated for marines. Freshwater organisms seem hard-wired to get by with less iodine.>
Thank you again.
-Margie
<Most welcome. Neale.>

Crayfish plague?    10/28/16
So it's been almost a week of diligently dosing iodine into my p.clarkii ghost's water and I am pretty convinced that it isn't a problem with his moulting because he is still in the same state as before, maybe even less energetic.
<"Post hoc, ergo propter hoc" is something to beware of here! Just because once thing follows another, doesn't mean they're causally linked. In this case, the failure of the iodine to dramatically improve things doesn't mean the iodine isn't helpful or wasn't the issue -- it might simply be too late, or alternatively, things might have got worse without the iodine. So keep an open mind. Iodine is absolutely essential for crayfish, that much is accepted by all the hobbyists keeping them nowadays, especially those keeping expensive and rare varieties.>
I suspect he is having crayfish plague and here's why:
1) His legs twitch uncontrollably as if he has no control over them (did some research and that's a sign of crayfish plague). He cannot even move around to eat anymore so I try to feed him by picking him up, turning him upside down and placing pellets (which I softened by soaking them in water for a few mimutes) on his beak. He initially accepted a bit of the food but now it seems that he has lost his ability to squeeze and chew up the food with his beak.
<This just sound likes a stressed/dying crayfish. Not a symptom of anything else. The clinical tests for Crayfish Plague require examination of the blood and muscle tissues. Obviously if you're an ecologist who comes across a bunch of dead or drying crayfish in a river with otherwise excellent environmental conditions, Crayfish Plague is something to consider. But a single sick crayfish in an aquarium? Nope, Crayfish Plague is kind of like "Swim Bladder Disease" in fish -- i.e., meaningless, and just another way of saying "sick and dying".>
2) On the underside of the tail where his pleopods are, his flesh seems to have become transparent almost to the point where his alimentary canal is fully visible (I think this is another sign of crayfish plague correct me if I'm wrong
<Again, indicative of a sick/dying crayfish. Their tissues do indeed change colour (think about a cooked shrimp versus a live one) but in the case of Crayfish Plague, one common symptom is darkening of the muscles where the legs (pleopods) attach to the body. There are some photos you can find via Google, but I stress, a sick Crayfish will look more or less like this, whatever it's dying from.>
All I can do now probably is to watch him die in his tank, I've probably already done everything I could to save him.
<I agree, but there are a few things left. Substantial, daily water changes. Increase aeration. Check hardness and pH. Don't force feed, but do try and feed every couple of days, even if only a small bit of white fish fillet held in front of the mouthparts. Crayfish are hardy, and have come back from seeming death.>
Even if there's treatment, I probably wouldn't have enough money to buy it for him. This will probably be the last crayfish I keep, unless I can get over this one's imminent death.
<I do suspect you've been unlucky, and will direct you to the excellent PetShrimp.com forum, which has a crayfish section where I think you'll get quick, specific help if you can post photos as well as descriptions:
https://www.petshrimp.com/discussions/viewforum.php?f=3
While I don't agree with this guys on everything (the site owner isn't a big fan of iodine, for example) they're very thorough and helpful people.>
Thanks for all the help that you guys have previously given me though :)
<Most welcome. Neale.>

Yabbie Question for the forum      8/26/16
Ammonia = 0
Nitrites = 0
Nitrates = >40ppmm

GH = 29*
Kh = 5*
One drop iodine during 1/4 water changes each week.
I teaspoon aquarium salts at each water change.
I chunk of cuttlefish bone, two filters with aeration, two good hiding places.
Hi there,
I hope you are still answering Yabbie questions!
<We try!>
I have a blue yabbie, approx 10cm in length in a 38 litre tank - have had him for 5 months, for the first month he lived in a 25 litre tank. He moulted after 4 weeks and then again 4 weeks later but not since.
<Moulting becomes less frequent as they age. At maturity, they may moult very infrequently, maybe even once a year, if that. In any case, the triggering factors are multiple, and not just good diet, but also availability of calcium and iodine, temperature, even day length.>
About 6 weeks ago he escaped from his tank during the night when one of the children moved his tank cover, and was found at midday the next day on the floor under shelves near his tank - so was out probably for at least 8 hours- and returned to the tank (I put him straight back in, not realising that wasn't a good idea).
<No worse than leaving him out of the water! Definitely did the right thing.>
He lost the top 2/3rds of his large antennae during the escape and was very 'wobbly' when moving around for about a week afterwards, kept his tailed curled under all the time and generally looked a bit traumatised.
<I bet.>
He is now physically as he was before, but has been very reclusive and has not eaten much (I used to feed him algae wafers daily and occasionally dried shrimp or goldfish pellets, but less frequently now since he doesn't seem hungry). I see him pick something up food every four days or so but often he just drops it immediately and goes back to hide. My questions are - would the loss of antennae make him unable to detect or eat food?
<Absolutely! For a crayfish, these are the main instruments used to sense their world. Their eyes are far less useful, mostly used to detect movement and shadows that help avoid predators. But the antennae are used to detect dissolved chemicals and probably vibrations in the water too, and these
help them find food.>
Is 3 months too long between moults for such a little guy?
<Nope. Wouldn't worry about. I don't know if crayfish ever stop moulting completely, but they can certainly go months between moults.>
GH seems high - is it too high?
<Nope; hard water is ideal. Actually, carbonate hardness is even more useful. Your water is fine.>
His tank is in a warm low-light bedroom and is generally at 22-23 degrees - should I move the tank or make it warmer?
<Neither. But the only thing I'd suggest doing is freshening up the tank a bit. Give it a good clean, and do a series of decent water changes across a few days, perhaps a third of the water each day, so that his entire world improves. Get rid of any decaying organic muck that will be sucking oxygen out the water. Don't bother adding food for a while if he's not interested.
After a week of starving him, offer him something really good, like a small unshelled shrimp or a small opened mussel. Something with a good strong
smell. See if he shows an interest. If not, remove; but if he's happy, let him dine like a king!>
Have you heard of long-lasting damage from an escape or am I anthropomorphising him?
<Neither. Just because an animal doesn't think like a human doesn't mean it doesn't think. In his own way, yes, he had a rough time and it'll take a while for his brain (such as it is, perhaps) to comprehend that his life is now safe and cozy, and that he doesn't need to stay in an alarm mode. In the wild, crayfish do get beached when it's a dry spell, and might be holed up in a burrow for weeks. Their bodies switch over to a sort of suspended animation that keeps them from needed as much food or oxygen. All very useful. But if he's been switched into this mode now, it might take several
days to switch back to his normal mode. Make sense? I just don't know. But I'd speculate that if he's moving about and breathing, he'll be fine, but he just needs time to readjust.>
On that note, what can I do to cheer him up, and/or encourage mouthing so he gets his antennae back?
<Moulting will fix any/all physical damage like this. May take time though, i.e., more than one moult.>
Many thanks for the amazing website, I use it a lot.
Kirsty
<Welcome. Neale.>

Crayfish iodine        4/4/16
Hi!
<Matt>
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
:
http://www.wetwebmedia.com/fwsubwebindex/fwestcycling.htm
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

Hi!
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?
<No>

Because the filter is pretty good, and oxygen supply shouldn't be a problem. Right?
<Correct>
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.
BobF>
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:
http://www.wetwebmedia.com/wwmadminsubwebindex/bobfbio.htm
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>

Crayfish Worms       2/18/16
Hello,
I have a 55 gal tropical community tank with various fish (angels, Serpaes,
<Eek! Nippy little nippers, these. Odd choice for life with Angels and long-finned anything.>
Longfin danios, red line tetras 2, and a red fin) I also have a blue crayfish. I have noticed worms on him and performed a water change and used a soft toothbrush to get the worms off.
<Sure.>
I know that they are harmless to the crayfish but am wondering if they are harmful to the fish.
<Very unlikely. Do perhaps replace moults immediately, to prevent re-infection so far as practical. But because consuming moults provides important calcium to the Crayfish, provide an alternative, such as unshelled shrimp. Oh, and keep dosing with iodine. Very helpful to crayfish. Use marine aquarium iodine, one-half the stated dose should be ample.>
I would prefer to not treat the tank as it just causes more issues in the long run. All the water parameters are good so my only concern is the worms
<I would not worry unduly for now.>
Thank you :-)
Nicole
<Welcome. Neale.>

Crayfish With Brown Leg; no rdg., data of use        10/15/15
Hello,
For four years I've kept a female crayfish who has lived well, with no signs of unusual behavior. I feed her every day with True Fin: Crab and Lobster Bits,
<I would expand this diet. See WWM re crayfish feeding
.... the FAQs>
and clean her tank whenever acceptable.
<Should be done on a scheduled basis; best weekly. See WWM re this as well
>
In the four years I've owned her she has had three molts.
<Stop: have you searched, read on the site re Cray care? What re your water quality, iodide use? There is NO SENSE in your writing w/o using the site.
Start here:
http://www.wetwebmedia.com/CrayDis5.htm
and the linked files above. Bob Fenner>
During the third and most recent one she lost one of her claws, but it seemed to have healed and didn't cause any problems. It happened today though, that when I woke up I found her on her back. Thinking she probably fell from unbalance, I carefully turned her right side up, but that was when I noticed that there was a problem. She seemed to be struggling to stay at the bottom, and would not move for a long period of time, except for small twitches with the antenna and legs. After she had stopped moving I noticed that her fifth walking leg was a deep brown color, unlike her original color of creamy white.
The tips of her antenna were also slightly curved at the tips. For a while she stayed still, with her abdomen tucked underneath her. After a while though she placed herself in a vertical position with the abdomen still underneath her, and her legs hanging out in different positions. Then she went back into her original position with only her legs and antenna moving. I'm highly concerned because I've never seen her do this before, and it doesn't seem to match with her usual molting behavior. Please help.
Sincerely,
Nina

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

Hello,
<Shalom!>
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.
<Indeed.>
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.>



Pet yabbie problems. Perhaps I2        9/9/15
Hello, I have a pet yabbie (Mr. Yabs) and have had he/she? (not sure gender)
<Can be determined externally. See WWM re>
for about 7-6 ish months I think?. Anyway, normal Mr. Yabs is very active and loves running around the tank and exploring. For the past around 2 months Mr. Yabs sits in his cave with his tail curled (no eggs in their in case he is a girl) and has no interest in food, I give him his favorite...worms, carrots, meat and other veggies and he just sits in his cave with his claws hanging low. I am not entirely sure if he gets his food in the end. The only time I have seen him is once recently when he moved very slowly just from one side of his cave to the other, which is not a gigantic space. Also he has not shed in at least a month- 2 months and I am not sure why.
Thanks for the help (Sorry if this isn't the right spot to look for help)
<Oh; this is it>
Zoe (pet owner).
<Do you supplement iodine (actually -ide/ate)? Necessary. I take it the water is suitably hard and alkaline for the species... DO read here please: http://www.wetwebmedia.com/CrayDis4.htm
and the linked files above...
Till you understand...
Enough to formulate a plan (dosing I2)
Bob Fenner> 

Blue lobster!! HELP!       8/23/15
So this is Bernie, I love him more than life itself. What's wrong with him?! This thing on his eye started out a few days ago and looked like a spider web and now it's progressed. I'm worried....
Please any info on this eye condition would be wonderful! I think he is completely blind by it now, I just want to know if it's hurting him.
(There's plenty of room in the heart for a special needs blue lobster).
<Let's simplify things by first asking you one question:
What source of iodine are you providing your crayfish?
If the answer is "none" then that's likely your problem. Crustaceans, particularly the bigger ones like crabs and crayfish, need a supply of iodine to moult properly. Without it they suffer from all sorts of
developmental problems, and sometimes simply die. Since crustaceans can "self repair" with each new moult, providing iodine can fix some developmental abnormalities, though typically over a series of moults rather than just one. It is possible your crayfish is suffering from an infected wound, bad genes, or exposure to a toxin such as heavy metals (copper, most commonly; a good marine aquarium store can check your tap water copper concentration for you). But even with these, providing iodine would ensure your crayfish has the best chance of fixing itself. You can buy iodine supplements from marine aquarium shops, and dosing at half the amount stated on the package is normally ample for freshwater tanks. In marine tanks it's SOP to add iodine as often as daily, but once or twice a week should be more than adequate for freshwater crayfish. In addition, providing iodine-rich foods such as seaweed (Sushi Nori for example) and certain crayfish/crustacean specific foods enriched with iodine. These will give your chap a quick boost of iodine that may stimulate moulting and repair. Neither the iodine supplement nor the Sushi Nori are expensive, so you shouldn't find any of this too onerous. With luck, you'll see your crayfish patch himself back together across the next few moults. That's the theory, anyway! Cheers, Neale.>

Crayfish no longer eats his exoskeleton.         8/12/15
I have a crayfish that I got for free when I went to buy a goldfish.
Apparently he came in with a shipment of fish so they couldn't sell him/her. I was thrilled to say the least. He has shed his shell almost once a month the first year and less frequently now (maybe once every 2-3 months. He was about an inch and a half when I got him now he is about 7 inches. His last two molts he didn't eat the exoskeleton Any idea why?
<Mmm; almost certainly "something" lacking in the environment and/or nutritionally. Have you read on WWM re Crayfish health, nutrition? Do you supplement iodide-ate? Know what the water alkalinity is?>

Also my crab (Mr. Crabbs) seems to eat MORE before he sheds his exoskeleton. Any idea why?
<Oh yes; in preparation for the actual molt itself... takes energy and crustaceans swell up to break the old skeleton, get out... and need more stored food to generate anew>

I have had him almost 2 years. I change his water every month, have never added iodine or checked the PH.
<See above and WWM>
He is in a 5 gallon tank and seems to be very happy and healthy. I feed him crayfish food, algae pellets, bloodworm pellets, cucumber, zucchini, carrot, green pepper, apple, cashews and nuts and small pieces of shrimp from time to time. I have no idea what type he is or where he is from. HE is a beautiful reddish brown in color.
Karen
<I'd be treating your Cray akin to your Crab. Bob Fenner>

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