Crayfish, Crawdads, Yabbies, Ditch
FAQs on Crayfish Disease:
Crayfish Health 2,
Crayfish Health 3,
Crayfish Health 4,
Crayfish Health 5, Crayfish Health ,
FAQs on Crayfish Disease by Category:
Crawfish Pie, Let's Make a Crawfish Tank! By Gage
Harford, Invertebrates for Freshwater
Aquariums by Neale Monks,
Freshwater Shrimp, Crayfish,
Freshwater to Brackish
Freshwater Invertebrates/Use in
Aquariums, Freshwater Crustaceans for the Aquarium,
Fresh to Brackish
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:
Re: Blue crayfish injury 6/14/17
Yes, marine iodine, half dose as specified in your previous q&a's. Will it moult
<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?
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>
Yabbie Question for the forum
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
I hope you are still answering Yabbie questions!
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.
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
that wasn't a good idea).
<No worse than leaving him out of the water! Definitely did the right
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
curled under all the time and generally looked a bit traumatised.
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
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
and shadows that help avoid predators. But the antennae are used to
detect dissolved chemicals and probably vibrations in the water too, and
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
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
out the water. Don't bother adding food for a while if he's not
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
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
<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
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.
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
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
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
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.
Blue crayfish injury? 8/29/15
<Good morrow here now Sheila>
We have a question about our blue crayfish. He managed to climb up into a rock
decoration in our cichlid tank. He was in there for a full day and we could see
him, twice, try to get out and was unable to squeeze out the hole.
<Unusual.... should be able to get out of anything it can get into>
We left him alone while turning the rock cave upside down hoping he would get
out. We became concerned after an entire day/night in the rock/decoration so we
decided to break the rock to get him out. We did not break the rock where he was
but next to where he was. He was finally able to crawl out on his own but now we
can see what appears to us as "white
flesh" popping out the top of his shell right behind his head. He is now hiding
under a log, one he can't climb in, and is on his "tip toes" so to speak. Is
there anything we can do to help him?
<Yes; this physical injury will heal sooner given good water quality and
nutrition. Plus, I'd up the dosing of iodine (ide-ate actually) here.
and the linked files above; till you feel confident in how to proceed>
<Welcome. Bob Fenner>
Crawfish dying within 24 hours 4/10/13
<Hi Eric, Rick here>
I live near a store that regularly offers live crayfish for sale.
<I know you don't live near me, crayfish are a rampant invasive species
in Arizona and are therefore restricted by Game and Fish!>
With my young daughters prompting, I've tried twice to pick a lively one
out of the box and place it into a well established aquarium.
The test strips all read okay and I had a submersible filter in for
filtration and supplement air.
Both specimens died within a 24 hour time period.
After researching care for these guys, I can't seem to find a reason for
them not to be making it.
If there was something wrong with the tank, I would think they'd at
least make it longer than a day.
Any ideas would be helpful.
<The only thing that comes to mind for me at the moment is that perhaps
they weren't properly acclimated to the tank. What procedure did you use
to make the transfer from plastic bag to tank?>
Re: Crawfish dying within 24 hours 4/9/13– 04/10/13
Thanks for the quick response.
Honestly, I took them out of the bag and placed them into the tank.
Keeping in mind these guys were sitting in a crowded box with no water
at the store, I figured the sooner I got them into the water the better.
<Hmm. I'm not sure what you can do here because every acclimation
process always assume the fish starts in water. Could there have been a
large temperature difference between the bag and the tank water?>
The second time I tried, the crawdad lived over 24 hours in the tank and
was very active and feisty. Next day, he was gone.
<It certainly sounds like stress of some kind.>
I wonder if what they've been through to get to market is just so
they don't have much of a chance past a certain point.
<Possibly. You might try easing them into water. Empty your tank and
form the substrate so there is a hill. Put enough water so there is a
pond on one side of the tank and dry land on the other side. Place
the crawdads on the dry land part and let them enter the water on their
own. Once they are in the water regularly, add a half gallon at a time
until the tank is at the desired level. Also, take a look at this
website I stumbled across.
has some ideas on how to transfer, but again, it assumes the fish starts
in water. It might be that being out of water at the store is the
Their gills must be moist to work properly in air. Actually, as I
proofread and think about this some more, I wonder how long the fish has
been completely out of water. Could be the gills are already dried and
damaged before you bought the crayfish. - Rick>
blue crayfish stuck in shell 9/18/12
I bought a blue "lobster" from the pet store back in May, and this is
the first time he molted. I noticed his old tail is still stuck over the
new one. I'm not sure how long it's been like that since he molted while
I was sleeping. Do I just leave him and eventually he'll get it off on
Will this cause damage to his tail?
<Do you provide supplemental iodine supplement (actually iodate/iodide)
in the form of marine aquarium iodine drops? Failed/improper moults are
a VERY common symptom, result of not providing iodine. In a normal moult
the entire moult should come off and usually the crayfish turns right
round and eats it, recycling the calcium therein. If the moult doesn't
detach completely, that's bad, and tends to imply a problem with
moulting (ecdysis, do read online re:). There's no fix, and if the
crayfish will recover, it will under its own steam. But do acquire, use
iodine supplement (or at least an iodine-rich food, e.g., seaweed, sushi
Re: blue crayfish stuck in shell 9/18/12
<Just in case Neale is out for the day (he's in the UK), am responding
as this appears to warrant prompt response>
So don't try to pull it off? Just let him do it?
<Don't pull, let this animal "do it">
Will the iodine effect the
other fish (a Pleco and dwarf gourami)?
<Will not affect negatively>
And is the iodine with the saltwater stuff?
Last time I asked for it the employee gave me a strange look and told me I
don't need it.
<Search WWM re Crayfish and Iodide-ate... they DO need it, along w/
adequate alkalinity and alkaline earth presence. Bob Fenner>
Re: blue crayfish stuck in shell 9/18/12
So don't try to pull it off?
<Not a good idea.>
Just let him do it?
<If he can, he will.>
Will the iodine effect the other fish (a Pleco and dwarf gourami)?
<Well, since you shouldn't keep crayfish with tropical fish this is
normally not an issue. But no, the iodine supplement is safe if used as
instructed. You only need about half the dose quoted on the bottle.>
And is the iodine with the saltwater stuff?
<Correct. Do note that while we're throwing around the term "iodine"
here, speaking of the element, we actually mean iodide or iodate salts,
so NOT the iodine solution (tincture) used to clean cuts and sold in
If memory serves, it's potassium iodide that's normally provided to
invertebrates like crayfish.>
Last time I asked for it the employee gave me a strange look and told me
I don't need it.
<The world is full of contradictions. Do you research, reading and then
come to your own conclusions. There's an ample literature re: ecdysis of
crustaceans and the key role played by iodide/iodate. Cheers, Neale.>
blue lobster, injured 6/11/12
I have a blue lobster and have had him for about 2 months. Last night he
escaped from his tank and fell about 15 feet
onto tile. We found him still alive this morning (not sure how long he
was out of the tank) and put him back in his tank, but he isn't moving
much and appears to have trouble moving his left side. He did eat an
algae wafer we put into his tank, but still isn't moving much. Is he
suffering, or will be able to recover from the fall? We aren't sure what
<These animals can be very tough... even if the exoskeleton was
given good care, food... it should recover and molt to having a full
test in time. Read here re:
and the linked files above. Bob Fenner>
Re: blue lobster 6/12/12
Thank you for your reply. We'll see what we can do and hope he
makes a full recovery!
<Ah yes, BobF>
Re: blue lobster 6/12/12
Yes, about 15 feet. He got out of my son's room and crawled into the
hall and fell through the banister to the foyer below. It's a 2 story
foyer and there's no carpet so he fell directly onto the tile. My
husband found him on his back, but still alive.
<Yeeikes! And yay! B>
Crawdads pinchers 11/11/09
My crawdad is five years old. He was molting and his pinchers got
caught in the old and I had to help him. However, he was caught for
about seven hours cause I thought he would eventually get them off. Now
that they are free, his pinchers are upside down and he stays on his
back. It's freaky.
If I cut his pincher/pinchers off at the base, will he still live?
<I wouldn't pull the pincers (not pinchers!) off since that
requires a great deal of force, and you're likely to damage the
crayfish in the process. It would certainly be very traumatic for the
animal. Much better to let nature take its course here. Do note that
many "failed" moults come down to insufficient iodine, and
for freshwater crabs and crayfish, supplying iodine really makes a big
different in terms of success. Some crustacean-specific pellet foods
may cover this aspect of things, but otherwise use a standard marine
aquarium iodine supplement at about half the quoted dose. Cheers,
Found a crawdad in our backyard 6/18/2009
Hi my name is Deanne I live by Castaic Lake. Today my daughter found a
crawdad in our backyard, and we have no clue as to how it could of
<Most often carried/dropped by dogs, cats, raccoons, birds, and so
We had Terminex come and spray for pesticide yesterday, and Im afraid
it might of ingested some of it.
<May well have done, or else simply damaged or stressed by being
carried and dropped out of water.>
He was still alive when we found it, but moved it a couple time not
sure where to put it. We finally decided that the fish tank was the
best place for it. It seemed to be doing fine, moving around etc, but
after a while
it kinda just fell over onto its side and hasn't moved since.
Nothing but a few leg twitches and a claw closing but tats it, is there
anything we can do for the poor thing?
<Probably very little; by all means improve circulation and
oxygenation, and ideally provide water that isn't too warm if this
you live in a temperate zone area rather than the tropics. Observe, and
if the thing dies, do remove the body quickly.>
<Good luck, Neale.>
Blue Crayfish Dear Crew, especially Sabrina, <Sorry, I
stole the email from Sabrina, Gage here, your local Crawdaddy
fanatic.> I have a little blue crayfish, nearly 3" long, 2
years old, called Lopez. At the last molt (Sunday) he got a leg stuck
and when he finally got it out, the leg/pincer was at an odd angle,
kind of backwards, clumsy looking. He is moving and eating (lots) and
can still use the leg and pincer, but it is certainly not right. It is
bent backwards and gets in his way when he tries to hide in his
jar/burrow, though he gets in in the end. I am wondering whether to
somehow tweak it off (ouch) so he can grow a new one. But really, I am
scared to hurt him and would rather think he will be fine and that he
is not in pain as he is. What do you think? How can I tell? And if you
think I really must tweak it off, any advice on how to do so...?? I
really like this little fellow and want to do my best for him. Any help
appreciated. <I vote to leave it, I do not think it is worth the
stress of breaking it off. Chances are he will correct it himself in
the next few molts. Best Regards, Gage> Cheers, Andy
Blue Crayfish, cont'd Many thanks for the swift reply. I
am inclining towards leaving it. <I definitely agree with Gage here,
better to leave it.> If he was in pain, I think I'd see
differences in his behavior wouldn't I? <I would think so, yes.
If he's eating, acting normal, let 'I'm be.> He looks to
be acting as usual, but with a dicky leg... Andy <I would strongly
recommend adding iodine to his tank if you don't already, and if
you do, to increase the amount by just a bit until his next molt. I use
Kent marine iodine, at a rate of one drop per ten gallons every week.
Wishing your lame pal a swift recovery, -Sabrina>