Crayfish, Crawdads, Yabbies, Ditch
FAQs on Crayfish Disease:
Crayfish Disease 1,
Crayfish Health 2, 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
Lobster trouble. Cray hlth. 6/27/12
Hey, I'm Jordan. i am new to this but here i go.
I recently bought a lobster. I believe it is a blue cobalt lobster? Or
an Australian red claw... It has red dots along its tail, cobalt in
colour, at a small portion of its claw being red. I recently noticed
worm like parasites on it. Its mostly on its underside, its joints and
the cracks along it's shell. Its mostly in it's dents. The parasites
have two feelers and move about a single spot. They are white in colour
and about 1mm. I really need help and a solution to this problem. Im a
newbie. Thanks for your help.
<Mmm, yes; we've had similar accounts. Do read here:
and the linked files above. Bob Fenner>
Blue, the blue lobster/crawfish 6/23/12
Hello, I just have a inquiry about behaviour. 2 weeks ago, I picked up
what was titled a blue lobster.
<In the US at least, almost certainly the blue version of the standard
crayfish species Procambarus clarkii, the species farmed and eaten
across North America and elsewhere.>
Massive sale 85% off the regular price. He was about 1 inch long and
later I noticed he was missing about 60% of his legs
<Like all members of the Decapoda, crayfish have ten legs, i.e., the two
pincers and eight walking legs. There are other appendages to be sure,
but these are specialised in other ways, such as the swimmerets on the
So, if he has 60% of the original ten legs (including the pincers) he's
down to just 4 legs (including the pincers). Does this help?>
Currently I am setting up his own tank that should be fully cycled end
of this week ( I tend to cycle my tanks for at least 3 weeks before
adding anything I want to keep, with a few fish I would other fish feed
to betas or a fish I have yet to identify) Blue is currently sitting in
a breeding basket with a house and a plant and a baby molly. This tank
every thing is in the right range, pH is a little high for Blue (7.9) as
this is my live bearing tank. He just went through a molt.
<Good. Now, be aware the first moult is the easy one. It's the
subsequent ones where things go wrong.>
He did not really get any bigger (most likely as he re-grew most of the
<Could well be.>
That being said. I was expecting him to hide in his house. He is not. He
is wandering about following the baby molly out in the open. My question
is, as this is generally abnormal behaviour after a molt, do I need to
<Nope, don't worry.>
Or is he just a strange little critter? He has been in the breeding box
for 2 weeks now, could be he knows its safe?
<He doesn't "know" anything. But crayfish are opportunistic scavengers,
and by their very nature explore their territories and try to either [a]
eat or [b] swim away from anything else they bump into. It's a simple
Needless to say, both live plants and small fish are dinner items,
sooner or later.>
Oh he does get lots of different foods, shrimp, blood worms, flakes,
shrimp pellets, spinach, algae wafers, to name a few, and I add the reef
iodine as well.
<Ah good. That's the key. Green foods, calcium and doses of iodine.
Meaty foods are treats, once or twice a week, compared to the importance
of greens and unshelled prey animals (krill for example).>
<Most welcome, Neale.>
albino snow crayfish 6/19/12
I have a albino snow crayfish in a freshwater tank. I have had him
sometime and he has molted a couple of times but hasn't for a while now.
I changed the water and cleaned the tank like I usually do and added all
the tank care chemicals I always use. But for some this time he
is acting weird walking around with his tail curled under him. Won't eat
the food he usually loves and doesn't stay in his usual hiding spot.
Should I be concerned?
<I would be, yes. Do check the basics. Is the water temperature right
for the species? The usual Snow Crayfish of the hobby is an artificial
form of Procambarus clarkii, a species best kept at room temperature
(around 18 C is ideal). Although not fussy about water chemistry, soft
and acidic water is best avoided, so you're aiming for about 10+ degrees
dH, pH 7-8. They are herbivores with a strong taste for carrion, so a
diet based around algae wafers and green foods (cooked peas, blanched
lettuce, spinach) will provide the main nutrients while occasional
crushed snails, unshelled shrimps and whole lancefish (i.e., food with
shells or bones in them) provide the extra protein and calcium they need
to grow. All Crayfish benefit from additional iodine, which you can buy
in marine aquarium shops for use in reef tanks. Add at one-half the
dosage recommended and you should find your Crayfish is healthier and
moults successfully. Last but not least, remember about their
intolerance for many "medicines" such as copper and formalin. Many of
these can be lethal to Crayfish, and copper can also be present in tap
water, so remember to use a water conditioner that neutralises copper.>
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>
Red covering crayfish eyes... no useful data or rdg.
I have a freshwater dark blue crayfish (Rock), he is about 2.5 years old
and has lived in his tank with 3 African Cichlids for about 1.5 of those
years. His behaviour hasn't changed at all but he has something red
covering both his eyes now. Im not sure he can see out of them anymore.
One eye is completely covered and the other one is about 80% covered.
There has been no changes to water as far as I am aware. Any ideas what
this could be?
<Need information re water quality, foods/feeding... Does this Cray shed
his exoskeleton regularly? Does it ingest the cast off to replace
minerals lost? Do you treat the system w/ iodide-ate? Please read here:
and the linked files above. Bob Fenner>
Re: Health Concerns with Blue Crayfish 5/1/12
Hi again Bob,
Thanks for all your help in the past. Our blue Cray seems to be feeling
better now. Water levels have been stable for about three or so weeks now.
She's stopped laying on her side and looking miserable. We think she may
have just been in the process of laying her eggs when we saw her appearing
so uncomfortable. Her eggs are still black and she's retained all of them on
the underside of her tail. She's been eating every few days and is fairly
active. We're assuming that the eggs are unfertilized, but we'd read that if
they're unfertilized that crays will often drop them. She hasn't dropped any
yet and is very protective of them, so we're not sure what that means.
Recently we started noticing that some of the eggs were turning a pinkish
orange color and developing a fungus-looking cloud around them. She still
has black eggs that appear unaffected by this, but it definitely is
spreading, as now she has several large clumps of these orangish eggs coated
in a soft white fuzz. Are we correcting in assuming that her eggs have
If so, why hasn't she dropped her eggs by now, since they're likely
infertile and diseased?
<Sometimes they become so sticky, they stay in place>
I've been researching fungal infections and treatments for invertebrates
and some of them sound just plain scary! From what I've read Methylene Blue
seems really messy, dyes everything, and can mess with the balance of the
cycle - which is exactly what we don't want - and also seems to be best for
dips. We're not sure if that's the right solution for her.
<No treatment at all>
I've read that Malachite Green can be highly effective against fungus, but
dangerous and deadly to invertebrates. Is this true?
If so we certainly don't want to use it for our blue Cray, and that would
also nix out SeaChem Paraguard as it contains Malachite Green. Interpet
Anti-Fungus looked like it might be an option, but is hard to find in the USA
and we want to start her on treatments right away.
The options that look the most promising are Esha2000, Mardel Maroxy for
True Fungus (is there a difference between fungus and true fungus?),
<Yes; most of what people label "funguses" are actually bacteria... need
microscopic examination to tell>
Mardel Maracyn-Oxy (non-antibiotic), and Mardel Maracyn Powder or Tablets
(antibiotic). From what I've read they all appear to be non-toxic and safe
for invertebrates, and they all appear to treat fungus. Aside from that, I
have no idea what the difference is between all those Mardel products, I
don't know if we should be looking for an antibiotic or non-antibiotic
treatment, and I have no idea which ones would be best or recommended. Any
<Yes; to not treat period>
Also, now that the eggs have fungus, at what point will they fall off or
will she drop them or pick them off?
<Will be shed w/ the next moult>
Will the anti-fungal treatments help this problem, or should we do something
to scrape the eggs off of her? Is there a safe, non-traumatizing way to do
As always, thanks for your help!
P.S. I have also attached a few images of her with the fuzzy eggs.
Health Concerns with Blue Crayfish 4/20/12
Five weeks ago we purchased a blue crayfish from a local fish shop. We
don't know how old she is, but she is about 4" long. She lives by
herself in a 20 gallon tall aquarium with four artificial plants of
varying size, a thick layer of artificial (blue and white) gravel -
which we are hoping to switch out for natural stone gravel in the
future, and a large piece of slate rock that is propped up by a smaller
piece of slate to fashion a cave for her to hide in. Her tank also has a
hanging submersible heater which keeps her water around 71-72°, a Top
Fin filter system, and a pump with wall bubbler for aeration. We do not
have any other fish or live plants or animals in the tank. Her diet
consists of frozen peas, crab & lobster sinking pellets, algae rounds,
and frozen bloodworms. Her water is about 3/4 RO water with 1/4 tap
<Why the RO? What aspect/s of your source/tap water are you trying to
We added the standard amount of tap water dechlorinator prescribed on
the bottle and have switched out her filter's media cartridge twice
since we've had her because the color on the gravel keeps flaking off
and clouding the filter, which is why we want to replace the artificial
gravel with natural stone gravel.
We are new to owning a blue crayfish and, because of a lack of research
and understanding on our part, we did not know about the fishless
cycling of a tank before introducing a fish into it. We had already
purchased our blue crayfish. So we bought an API Fresh Water Master
Liquid Test kit and have been testing the water for pH, ammonia,
nitrite, and nitrate every other day. It took over four weeks for the
tank to cycle. Not wanting to speed along the cycling process with any
kind of BioBoost product, we used the prescribed dosage of SeaChem Prime
to help detoxify the ammonia and nitrite while the ammonia
spiked (up to about 1.0 for a week), and the nitrite spiked (up to about
5.0 for nearly two-and-a-half weeks).
<Both VERY toxic>
It was awful - our Cray hid in her cave the entire time, hardly ate, and
spent her days and nights digging and rearranging her gravel beneath the
rock. Every now and then she would come out to visit and stretch against
the tank walls, but she wasn't being active outside the cave and she
clearly wasn't happy about it, understandably. We think the only reason
she made it through the cycle alive was because of the SeaChem Prime.
We are now at these levels: pH - 7.6, ammonia - 0, nitrite - 0, and
nitrates - 10.
About a week or so ago I added a few drops of liquid iodide to her tank
as well to help her in case she was molting.
I don't know if we should be adding iodide to help her molt, or calcium
to strengthen her shell, as it kind of seems like crayfish need both. Do
you have a recommendation of what to use and when?
<Yes... posted on our site. Read here:
and the linked files above>
Over the past few weeks we've noticed some odd discoloration on her. She
was a nice bright blue when we got her. Now she has some red on the
lower edges of her tail and bottom of her thorax. It's a gradual fade
from blue to red, not patchy red blotches. We've also noticed that she
now has visible dark brown lines on her abdomen, specifically in between
the little segments of her tail when she curls it under her.
<I see this... troublesome... Perhaps a sort of chemical burn from the
prior ammonia, nitrite exposure... Might be due to a nutritional
We've read that crayfish discoloration can be caused by a number of
factors including stress, dirty water, poor water conditions, and
Because of the tank cycling we know that she's likely been stressed and
dealing with poor water conditions for the past month. Luckily, they are
back to normal now. Do you think that this could be the cause of her red
and brown discoloration?
If so, how long do you think it will take for her coloration to return
<Next molt, two...>
Or could this be a sign she is due for a molt? We are not so worried
about the red coloration, but the brown coloration between her tail
segments concerns us.
Also, we were advised by a local fish store not to do any water changes
while the tank was undergoing its first cycle.
<See WWM re... I would do such changes if NH3, NO2 exceeded 1.0 ppm,
However the water was getting dirty from food she was not eating when
her appetite decreased, and when her ammonia and nitrite levels were at
their peak we did a few 20% water changes with gravel vacuuming.
But not much beyond that because we wanted to wait for her water
conditions to level out before we started a pattern of bi-weekly of 25%
water changes with gravel vacuum. So I suppose it is possible that her
water could be fairly dirty (and it is when we stir up her gravel),
although it looks pretty clear when it all settles, with the exception
of the gravel color flaking off. But now that her tank has cycled we
want to start changing her water and vacuuming her gravel more often.
How often and how much can we clean her gravel without risking jump
starting another cycle?
<Now, no worries>
She also has a large rust-colored spot on the top of her shell near her
head. It appeared about three weeks ago and has not really shrank or
changed any since then. It has grown some. It doesn't appear to bother
We thought it was caused by her slate cave. She relocates her gravel
frequently, builds it up, then leaves herself no room to crawl out of
the cave. When she tries to crawl out, since it is the highest point on
her body, it scrapes against the top of the rock. We've been assuming
that the scraping is what caused the rust-colored spot.
We noticed it after she'd blocked herself in for the first time and was
scrapping again the rock to try to get out of the cave. This happened
just before the ammonia spike, about a week after we first got her. But
then I recently learned of shell rot - and that it if often caused by
poor water conditions and leftover food in the gravel - both of which
were a problem for us, and became concerned that perhaps that is what
the rust-mark is or that maybe that's what the brown on her tail is.
Do you think this is shell rot or just a scrapped shell from the rock?
How can we identify shell rot? Is there a treatment you'd suggest?
We've read that Melafix is a common treatment
<Is garbage... may alter nitrification>
(but isn't very effective) and that salt dips or adding a small amount
of salt to her tank are the preferred treatment and are our best bet. We
spoke to someone at the local fish shop who recommended that we just add
a bit of salt to her tank and NOT vacuum her gravel, change her water,
change her gravel, or give her a salt dip until she shows signs of
improvement because if she's already sick the stress of these changes
could do more harm than good.
Finally, she also has one little leg in the back with pinchers that are
stuck open. There is a small red spot right in the joint and she picks
at it and scratches at it. Do you have any idea what that might be?
<Again... the same causes>
Since her water has stabilized, she's started eating more (though less
than she did at first - now she eats about every other day), but she
remains fairly active, constantly moving her swimmerets, always
rearranging her gravel, and occasionally coming out for a stretch or
quick walk around the cave.
We are just, obviously, very concerned about the discoloration, possible
shell rot, and any potential long-term damage from the water cycling.
Since we are new crayfish owners we don't know if this is a sign of
molting, a temporary repercussion of the poor water conditions during
cycling, or if there is something more serious going on here (and if so,
how to treat it).
What would you recommend we do?
<Read... I would have use Dr. Tim's One and Only or the Fritz or other
bacteria "starter culture", but now it's too late>
The first two photos are her when we first got her. The second two are
Any help you can provide us would be extremely welcome and appreciated.
<Do write back after reading if you have further questions, concerns.
| Re: Health Concerns with Blue Crayfish
Thanks so much for your reply back. The RO water we are using is to dilute
the high level of pH in our tap water (about an 8 normally). With the RO the
tank water is around a 7.6.
<Mmm, for this species of Crayfish either is fine>
We have some new developments with our blue crayfish. Last night she was
scratching under her tail a lot, but she came out for a few laps around the
tank. As I mentioned in my prior email, her appetite has decreased, she's
stayed mostly hidden in her cave for the past month, she's been rearranging
her gravel endlessly, and we noticed black discoloration on her tail. We've
attributed her odd change in coloration, lack of appetite, and hiding to the
rough first cycle she survived though. She seemed to be feeling okay when we
left for work this morning, and ate about half of an algae round.
Tonight we came home from work and found her laying on her side in the cave
with her tail curled up completely under her. She seemed very very
uncomfortable and the situation looked grave. Then she started shifting and
we noticed a whole lot of black under her tail. Upon further examination and
lots of reading online, we've discovered she has tons of tiny little black
eggs! All we can think is that she must have been pregnant when we got her,
but we had no idea.
<Mmm, not pregnant... these eggs are not fertilized>
The more reading we did, the more others commented that their blue Crays hid
all the time, dug the gravel a lot and lost their appetite before laying
eggs...so it all kind of makes sense now.
Also, the black on her tail makes sense now too.
Now, of course, we have a whole new world of questions.
1. She looks SO uncomfortable. For the past several hours since we got home,
her tail has been tightly curled up under her, holding the eggs. She lays on
her side, then moves and tries to get comfortable, then shifts again, and
keeps switching sides that she lays on, but she really doesn't move or walk
much, just enough to try to flip sides and get comfortable.
She just looks extremely uncomfortable and keeps laying on her side. In all
the other pictures we've seen online of other blue crayfish with eggs, they
are all standing up and look almost normal. Is it normal for her to lay on
her side and look so miserable while laying eggs? How long can we expect
this to last?
<Not normal to lay on side... don't know how long the behavior will
2. How long will these eggs stay with her under her tail?
<See/read where you were referred to... days to a week or so>
Will she drop them on the tank floor and let them hatch there, or will she
hold onto them under her tail until they hatch? If so, how long until they
hatch? Will she seem so miserable the whole time it takes them to hatch?
<They won't hatch... this is a dioecious species... takes two to tango>
3. Is there anything we can or should be doing for her right now? We're
weary to do anything - change her water, vacuum the gravel, turn on her tank
light, feed her, etc. - because we don't want to stress her out right now.
4. We read that most babies don't make it. I think the black color means
they're fertilized, but again, we're so new to this that we really have no
idea. It's all a complete shock to us since we were honestly convinced she
was dying after that awful cycle and strange discoloration. What do we do
with the babies? We can't keep them all (assuming any of them make it)
because we only have a 20 gallon tank and simply don't have room for them
all, but should we take them to the local fish shop to sell or remove them
from her tank once they hatch?
<The stress from being put through cycling, the nitrogenous waste exposure
prompted the egg production... close to death experience... Perhaps closer>
Again, any help or additional advice as to what we can do for her would be
Yabby's tail curl up, toxic water cond.s
Here I am asking for your help again. Missy (my female Yabby pet) has her tail
curled up to her body in the last two days. She held it like that all the time,
which is abnormal. Before she only did it when she needs to run or claim a rock.
Is that a sign of sickness?
<Mmm, maybe... perhaps a dietary shortage, water quality or reproductive
She is the only one in the 2" tank. I change water change 25% every week.
Ph is at 8 and 2 drops of iodine every time I change water.
The tank however is going through a biological cycle with
ammonia = 0.25,
nitrite = 5
<Even more so!>
and nitrate = 10. Tested last week. The reason I did not test this week is
because through internet reading, it seems best for the tank to go through the
cycle naturally, without adding any chemical liquid.
So if there is nothing I could do about it, there is no point to test the water.
But the question is am I right? Should I buy the Stress Zyme to speed up the
<It won't do this... stop feeding for now and read here:
and the linked files above. Bob Fenner>
Thanks so much for your time and help.
I think my lobster is ill. Cray hlth. 2/12/12
Hi I have a blue lobster which I brought off a friend 5 months ago, she has been
really active up2 now, but since yesterday she has been really lethargic, she
shed her shell about 2 months ago, which I removed from the tank after a few
hours, (I didn't realise I shud leave in there 4 her 2 eat) she hasn't eaten for
2 days now & is jus hiding under her bridge wiv her claws stickin out the side,
which she has never done before, normally she is all tucked up, I am really
worried she is dyin & don't no wot 2 do, please if u cud giv me some advice it
wud b greatly appreciated, thanx Danielle.
<Hello Danielle. I do need some information here. How big is the aquarium?
What sort of biological filter are you using? How often do you do water changes?
What foods do you provide? What is the temperature of the water?
And please, do try writing in English rather than text speak. We normally bounce
back "gobbledygook" messages but you were so polite I didn't have the heart!
Meantime, read here:
Re: I think my lobster is ill 2/13/12
Hi, thank you for getting back to me, she does seem to be ok today, she's moving
around the tank and looks a lot better, I think I was just worrying but want to
make sure just in case I am doing anything wrong as its come to my attention
that I don't actually know a lot about lobsters, so any information would be
<Do read those links.>
I'm not sure what size the tank is but its 1 1/2 foot long, 1 foot tall and 1/2
foot wide if that helps.
<18 x 12 x 6 inches. About 5.6 US gallons. Quite small.>
The filter I use is a Fluval underwater 1, (I got it from my friend with the
whole set-up she didn't really tell me anything else) The temp is in-between 24c
& 25c and I feed her blood worm & dillies and I do a water change every couple
of months. Thank you for your time.
<Do read, read, read. When you have specific questions, feel free to ask them.