Whether they eat fish in the wild or not seems to be not as relevant as whether they will eat them in the OP's tank or not. They appear to eat fish in tanks for a lot of people. Some good solid advice on preventing this would be better then a fight wouldn't it?
Shake and make up?
indeed Suzie and though, perhaps badly, that's the point i am trying to make. there is no doubt that, in nature or by nature, crayfish are not predictors. around 20% of their food intake is derived from "animal" sources.
In the wild, about 20% of their diet consists of worms, insect larvae and other invertebrates found on plants or the pond bottom. Much of this food is microscopic in size and found on or in decaying vegetation.
taken from
http
/aquanic.org/publicat/state/ga/crawfish.htm
the perception, many have, of this creature. seems to be dictated by looks, not by the nature of the animal. a flick through this thread will show a fair few who treat their cray as a pure carnivores, some even feeding live fish!! so it is hardly surprising that a cray that gets no food unless it kills it, turns into a killer. their food should in fact consist of, mainly vegetable matter, if possible slightly degenerated, and SMALL amount of meat or protein. the other problem associated with feeding a meat only diet, is bacterial infection. Crayfish are prone to getting these infections, and the problem increases with the water temperature. so it would appear that, feeding a meat diet, may cause more than one problem for Crayfish.
though by no means universal, the habit of keeping Crayfish at the wrong temperature, may also add to the problems. Crayfish are cold blooded, so if a Crayfish is kept at too higher temp, logic says, it will be more active. if you add this to the fact that water hold less O2 as the temperature rises. so you have an over active Crayfish who is struggling to get enough O2, a combination that is unlikely to help.
in some cases Crayfish are successfully kept in a community, there are more than a few keepers who have posted here, who do. so why does it work for some? well some could be, varnishing the truth, some may consider the odd fish loss ok and not report it. but a few, including me in the past, have kept Cray and fish together with no losses, if you ignore my stupid mistake with the Bamboo shrimp. let look at some things that could make is possible.
First off, i am not suggesting that this will work.( though i claim 100%, err i have done it twice) i am not suggesting that people should do it. i am mealy suggesting it may be done.
there are two problems with baby crays and fish. the little ones need large amounts of protein, in nature this is dealt with by the infants feeding on their own siblings, so small bottom feeding fish may well be in danger. they also see fish as a danger or threat. this is something that will stay with the Cray forever, and as such may well cause the same Crays when older to treat all fish in that way. so first rule is:
1. never put immature, less than seven months old, crayfish in a tank with fish
following from the first rule, a mature tank and calm community, would also seem to be needed. fish consistently squabbling around the Cray is unlikely to make it feel safe.
2, always put Crayfish into a mature and stable tank.
hiding places, of several sizes are needed in one tank. now many fish also like these kind if places, this can lead to fish getting cornered. so
3, a large number of varied sized hiding places, with openings wider at the front than the back, making escape possible for the cornered.
4, NO predatory fish. a older Cray may not see fish as a threat, but it will soon learn if it is consistently attacked. Goldfish are an absolute no no, i am aware there are more, they will kill Cray at any chance, or be killed by the cray.
we have already talked about the diet requirements of Cray so
5, keep the Cray well fed. feeding mainly veg matter, and placing any meat directly by or near the cray, thus avoiding any problems with the fish getting there first
6, Cray need a high O2 content, though they are quite happy to live in water you cant see through, it must be oxygen rich.
7, if a community is what you are after, your tank will need to be a minimum of 50ukg.
and that for the most part is it, not a guaranteed formula, but a basis on which to work.
so why do some Cray act like predictors when kept in hobby tanks? is it us, and the way we keep them, that are the root cause of the Crayfish's bad reputation.
