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.>

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.>

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>