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View Full Version : how predatory are crayfish?



Lightning Bug
01-18-2011, 8:35 PM
how predatory has your crayfish been in the past? im curious to find out what they are compatible with as far as fishy tank mates goes. so come on, share some stories :)

Taysius
01-18-2011, 8:38 PM
Other than dwarf crays, I would never keep one with any fish that you would be upset to find missing. I keep mine with guppies and every now and again I find that I have one less guppy.

Lightning Bug
01-18-2011, 8:40 PM
what about clipping its claws? doesnt that prevent crays from being able to catch fish?

Piranha86
01-18-2011, 8:43 PM
what about clipping its claws? doesnt that prevent crays from being able to catch fish?
Yes, that would prevent it from happening, but IMO that's a terrible thing to do. If you already have a fish with the crayfish, get rid of one of them. Don't go chopping off its claws!

tanker
01-18-2011, 8:51 PM
what about clipping its claws? doesnt that prevent crays from being able to catch fish?


That's like cutting off the hands of thieves.

Lightning Bug
01-18-2011, 8:55 PM
maybe i can find one with small claws instead of those big lobster kinda things you see on some crays.

Optimus
01-18-2011, 9:26 PM
Some dwarf crayfish are the same size and shrimp so I'd look into that.

Fishlock Holmes
01-18-2011, 9:43 PM
My sister keeps a crayfish in a tank with a school of odessa barbs. They're not full grown yet, about 1.5-2", but they seem to be big enough and fast enough that the cray can't get them. She's never had any problems.

BrainLady
01-18-2011, 9:59 PM
Cut his claws off!!! Oh no, that is awful.

Taysius
01-19-2011, 12:32 AM
what about clipping its claws? doesnt that prevent crays from being able to catch fish?

Seriously? That's just not right to even consider. I say if you really want a cray, then set up a small tank for one. I have a large cray in a 20 long but most species, the North American ones anyways, are fine in a 10gal for life.

021414
01-19-2011, 12:54 AM
A friend of mine had a crayfish and a goldfish in the same tank. Even though the goldfish stayed in the middle/top of the tank and the crayfish at the bottom, the crayfish decapitated the goldfish. Crayfish also eat each other if they are kept in too small of an aquarium.

katschamne
01-19-2011, 1:09 AM
I have had two crayfish and a dwarf platy in one tank. I ended up with just a crayfish in the tank. I know that it was enviably that the platy would end up as food but I had hoped that they would be OK for awhile until I had set up the new tank. The crayfish might be OK with fast swimmers like zebra danios but it is still a possibility that they will still get picked off.

As far as removing it claw, I do agree that would be cruel. If they happen to loose a claw they do grow back but it may take a couple of molts to grow back to it's normal size.

Khemul
01-19-2011, 1:15 AM
maybe i can find one with small claws instead of those big lobster kinda things you see on some crays.

Not sure if females keep the small claws when they get bigger.

From my experience if they are small enough that their claws are harmless they are food. If they are big enough to use their claws to hunt then you lose fish.

My latest one will get his own tank when he grows up (barely half-an-inch right now). The 2 main tanks have too many bottom dwellers to attempt it, and my goby tank...well they'll only hold out so long for melted butter.

kc1
01-19-2011, 8:06 AM
I've done it for years and never had any problems. most of the time it was with cichlids tho! never a casualty

aussie pride
01-19-2011, 6:17 PM
my cray (greg) has completely eaten a medium sized black moor. this was in the 29g he is in. one morning there was a moor, the next there just wasnt lol

spypet
01-19-2011, 8:40 PM
I've had several crays over the years, and they have one thing in common;
they are evil - pure persistent evil :FIREdevil:
anything in your tank that is smaller, slower, or dumber than your crayfish

will eventually become it's dinner.

Davy
01-19-2011, 8:57 PM
my sebastian is down right brutal!!

Lightning Bug
01-20-2011, 12:07 AM
ya, people are telling me about how bad crays are. besides, clipping the claws kinda takes the fun out of having one. since i love my banjos too much right now to get rid of them im just gona have to skip the crayfish thing for now. thanks :)

Lightning Bug
01-20-2011, 12:08 AM
......or i could find a way to put a tank divider in.

hage0245
01-20-2011, 12:33 AM
When I was ~4 I had my first fish tank. I don't remember what kind of fish we had, what size it was, or anything besides that we had crayfish. They would perch themselves on the highest rocks with their claws pointed towards the sky, and when a fish would accidently swim through the claws.....SNAP!

Needless to say, I don't like those little guys. I guess I am a little biased though haha.

Khemul
01-20-2011, 12:19 PM
......or i could find a way to put a tank divider in.
They'll probably climb right over the divider to the other side.

I've seen them make it to neighboring tanks at various chain stores around here even with a partial roof blocking their way.

floridaskunkape
01-20-2011, 12:30 PM
The Crayfish I've had were of the seafood store variety, red swamp something i think, but yeah, never able to have 2. always death. They will try to get fish till they eat them all, dark colored, slow moving, and ground sleepers first. They will escape and chase children. I tried to rubberband one's claws and put it in with a fire hap chiclid. Fish killed it, and pulled his claws off. somehow. I had the thought of superglueing their claws. It could work until a molt.

Taysius
01-20-2011, 1:18 PM
The Crayfish I've had were of the seafood store variety, red swamp something i think, but yeah, never able to have 2. always death. They will try to get fish till they eat them all, dark colored, slow moving, and ground sleepers first. They will escape and chase children. I tried to rubberband one's claws and put it in with a fire hap chiclid. Fish killed it, and pulled his claws off. somehow. I had the thought of superglueing their claws. It could work until a molt.


Or better yet, DON'T KEEP FISH AND INVERTS TOGETHER THAT ARE INCOMPATIBLE! Seriously people, would you superglue a fish's mouth shut for eating shrimp? :irked:

floridaskunkape
01-20-2011, 1:40 PM
apples and oranges.

Khemul
01-20-2011, 2:22 PM
Superglueing a crays claws shut would be rather cruel. Actually it'd probably be more humane to flat out remove the claws (still rather cruel to do).

Lobster have their claws banded, not because it isn't a horrible thing to do to them, but because they are food.

These are animals that use their claws for just about everything. Climbing, eating, hunting, establishing pecking order (this is usually why lobsters claws are banded), self-defense. The reason I say it would be more humane to remove the claws on a pet in this case is atleast the animal adapts to not having them, rather then constantly trying to use them when it can't. Think of it like tying a person's arms behind their back then making them go about their day, rather then glueing a fish's mouth shut.


Either way it probably wouldn't work anyways. Glue isn't as strong under water. It bonds and can be used to attach plants/rocks but if you ever tried to superglue things in an aquarium you'd see that it is VERY easy (compared to the bond formed outside of water) to break that bond.

spypet
01-20-2011, 3:46 PM
actually, they do most of their eating with the front two pair of clawed
walking legs. the main large claw is primarially for display and hunting.
I cut half the thumb off my crayfish's cheliped. they don't really care,
and it grows back as good as new after two molts. however, even this
strategy does not change the crays bad behavior, only it's effectiveness.

IMHO: it's really no different than trimming all 18 nails on my indoor only cat.

http://www.smithlifescience.com/CrayfishSideView.jpg

knifegill
01-20-2011, 4:45 PM
My baby crays (all 100+ of them) did a good job of eliminating all the bladder snails in their tank but have not eaten the planorbid snails. Don't know why, just suggesting it might be worth a try if nothing else.

spypet
01-20-2011, 5:19 PM
if a snail shell has either a trapdoor or a lot more space free deeper in the shell for the snail to escape, that may explain why one snail survived and the other didn't. observing ramshorn one might conclude that the extra free space is not only used as an out of reach safe room, but also to trap air that allows them to be more buoyant to feed on finer plants, and even to float and feed under the water's surface itself. the fatal flaw for the ramshorn vs any crayfish is the ramshorn shell is relatively thin and easy to break open.

captaincaveman9
01-20-2011, 5:28 PM
if you want something that looks mostly like a cray and have fish with it, look into bamboo or vampire shrimp

spypet
01-20-2011, 5:53 PM
fan shrimp are a great alternative to crayfish,
but many fan's starve to death in hobby tanks.

so from an ethical standpoint;
clip your crayfish claws a bit
or risk starving a fan shrimp.
kind of a jump ball there ;)

fishguychris
01-20-2011, 6:12 PM
what about armoured shrimp they have claws look

spypet
01-20-2011, 7:10 PM
claws on shrimp? so do all Macrobrachium species,
but I though we were here demonizing crayfish :duh:

Lightning Bug
01-21-2011, 3:47 PM
a glass divider will be fine. lowering the water level can keep a cray from getting over it.

the wizard
01-22-2011, 11:42 AM
I don't get the discussion of clipping claws when the question was about compatibility. The answer to the question is keep crays in separate tanks it really is that simple.

spypet
01-22-2011, 11:52 AM
clipping claws makes your crayfish more community tank compatible, just
like trimming your cats claws makes it more compatible with young children.
for sure separate tanks are best, but then "compatibility" is a moot point.

the wizard
01-22-2011, 12:22 PM
At this point we should agree to disagree. Your statement about cats claws seems to me like comparing apples and oranges.

thebrandon
01-22-2011, 3:07 PM
cat claws and cray claws??? Really??...I think it's completely wrong to clip off a crays claws just to make it suitable to be in a community aquarium. The fact is most crays are not suitable or appropriate for community tanks. There are occasionally some that tend to be more mellow and can live peacefully in a community. Here is a picture of my female cray with my two ropefish underneith her before she past away. This was an everyday thing for the fish to lay under her. She wasn't ok around snails or shrimp though. She did a good job keeping the BBA down and eating all the extra snails. Watching her eat BBA was weird.
http://i532.photobucket.com/albums/ee328/circleater/2010-07-13155650.jpg

spypet
01-22-2011, 6:03 PM
if you think such animal husbandry is "wrong" from some moral judgment,
then is it also "wrong" to confine fish to a few square cubic of water?
obviously we have a forum full of people who don't think that's wrong.

so the "wrong'ness" issue of clipping a few millimeters of crayfish thumb;
is being effective or not - I'm here to tell you it's VERY effective,
as it does zero harm to the crayfish, it's ability to thrive, and
increases it's potential to coexist peacefully with smaller tank mates.

just think of all the crayfish that get disposed of by their owners
because they didn't coexist in their community tanks. had this
clipping practice been maturely advocated, they'd be alive today.

thebrandon
01-22-2011, 6:28 PM
Responsibly keeping fish in a quality tank environment and mutilating (no matter how small) an animal so it can coexist in a tank are completly different.

spypet
01-22-2011, 6:31 PM
"mutilation" implies permanence.
clipping the claw thumb as I suggested,
grows back completely after 2 molts.

there is nothing "irresponsible" about servicing your animals to best care for them.
but if you don't have the stomach for it, don't do it - get more tanks, or more in
tank obstacles for them to avoid each other, bigger fish, or don't get crayfish.

my methods are only one of many semi-effective options available to you.

thebrandon
01-22-2011, 6:37 PM
If it's a continual clipping so it can co-exist in a tank full of food it is entirely permanent. Most cray fish like to eat fish. If you don't want one to be eaten by fish or to eat your fish, don't put it in the tank with your fish. Simple.

spypet
01-22-2011, 8:01 PM
are your fingernails "permanently" short
because you regularly trim them?
of course not.
your argument make no sense,
and are beside the point.

thebrandon
01-22-2011, 9:02 PM
You're comparing apples to baseballs here. Finger nails and crayfish claws may be made up of similar material and have regenerative properties but their similarities stop there.

Back when humans were more primitive our finger nails naturally wore down from the life styles, tools and environments we lived in.

A cray fish does not regularly cut it's own claws off because it is convenient and he doesn't feel like catching fish anymore. Your argument makes no sense.

the wizard
01-23-2011, 11:16 AM
Clipping a cray's claws, prevents the cray from being true to it's nature. It really is that simple.

spypet
01-23-2011, 12:30 PM
Clipping a cray's claws, prevents the cray from being true to it's nature.

so completely false unless you intentionally put a crays in your tank to hunt other animals.
my half thumb crays did not change in their behavior at all, they were simply less effective
at their attempts to hunt other community animals; the precise intended purpose to do so.

2rivers
01-23-2011, 1:46 PM
wow cut poor spypet some slack hes trying to inform you, sounds like he has more experience than most of you. Ive only used Crayfish as Bass food so I know nothing. Im not cruel and I dont think spypet is.Experimentation is a big part of fishkeeping, so exept good advice and try it out. If it doesnt work for you move on share your experiences and be nice please.

Greg6585
02-06-2011, 8:59 AM
Cut his claws off!!! Oh no, that is awful.


:mad2: I second that..very cruel

2rivers
02-06-2011, 11:15 AM
You dont cut the claw off. spypet is tryin to teach u how to trim the thumb claw. Listen better.

Drunkenbushman
02-07-2011, 8:55 AM
I keep a cray as a pet and would never cut his claws at all.

If you keep a cray you know they will hunt and attack fish. Keep fish in the tank that have the best chance of getting away or staying away and expect to have some losses. I do not agree with maiming the poor cray to prevent this.

spypet
02-07-2011, 9:50 AM
2rivers - thanks, but give it up - everyone reacts differently.
we only need to plant the seed of an idea in people's heads,
we don't need to stick around until it grows into a consensus.

raincoat
02-08-2011, 8:00 AM
2rivers - thanks, but give it up - everyone reacts differently.
we only need to plant the seed of an idea in people's heads,
we don't need to stick around until it grows into a consensus.

...inception.

But on a more related note, I completely agree that if you desire to keep crays in a community, you should be open to new suggestions and not be so quick to condemn.

Racheleeyore
02-08-2011, 8:30 AM
I have dwarf crays living with shrimp and fry - they get along as long as no one gets in the cray's face (silly curious fry). Then the cray rears up and the fry swims away.

spypet
04-22-2011, 10:20 AM
just to add something that surprised me with my CPO berried famale;
she alone shares a tank with a Vampire crab. I know from experience
that crabs can be stubborn and not move while crayfish try to pass by
and can pull crab limbs off in the process. however the CPO is half the
mass of the crab, and I didn't think I would have any issues with them.
till one morning I noticed a crab limb on the substrate, and sure enough
my one female crab was missing it. it just goes to show you how even
when it's relative size versus temperament, temperament will always win.

Kaosu
04-23-2011, 12:38 AM
to bad cray claws and cat claws/finger nails are nothing alike....
..it would be more akin to chopping off the tip of your finger(or your cats toes,,,just the tips) every few months..but its OK because it will grow back.

to the OP: i have just started keeping crays..they are fun little things^_^ but from what i have researched you try them in your tank to see if your cray will eat your fish , and run the risk of losing some fish you like. or you get there own little tank.
I have a marbled cray, she is in a 2.5 for now with a few guppy fry..that she ignores...snails on the other hand are her favorite! she destroys them...like 10 pea size ramshorns and pond snails a day....little monster^_^ good thing i have s surplus of snails.

I found most of it depends on the individual cray....and the species.

azolla
04-23-2011, 10:44 AM
Well, it really is about keeping everything appropriate. I have 3 P. clarkii crays in a 150g with large plecos and smaller armoured catfish. Never an issue for two years now. Also i have a colony of marms that never bothered even kuhlie loaches or pandy cories for years. It is a matter of putting the right critters together to begin with, and giving everyone the room they need to prosper. Did we all forget the golden rule of fishkeeping? RESEARCH!!!

Jessicaftw
04-24-2011, 11:22 PM
I have a few CPOs scattered about in my three tanks. I've noticed they all are different in temperament. One has been known to jump at a fish if it wants some food, but usually they swim off if they get too close to a fish or another cray. I love their personalities, really.

mela
05-19-2011, 4:25 PM
Hi All
I have 6 in one tank 8 crawdads in the other. Have no idea what species they are. Everyone has a different personality. The big plecos just toss them off. However there is a couple that the plecos let them crawl all over them. Looks like they are grooming the plecos. Lost two crawdads early this am. They were molting and were attacted. These little beasties are wunderful to watch.
The tanks are well water and local vegies from the pond.
Have never even concidered mutilating my crawdads.

Later
Mel

redperphexion
06-03-2011, 1:36 PM
Just wondering, does this "trimming" involve only shell-shortening/dulling, or cutting through actual meat and connective tissue?