Captivity paranoia

[fat meloe!]

I've been pondering this issue for quite a while.

Fishes in aquariums generally experience conditions that are quite different from those in natural habitats. For example, omnivorous fishes may partition their resources so that each species semi-specializes in certain foods to avoid competition; when in the tank, such fishes are often given similar diets and need not compete very much.

Of course, not all unnatural conditions produce negative results. But how many unintentional and troublesome side effects are our fishes (or even other non-fish pets) experiencing? For example, inbreeding in animals is well-known, and Practical Fishkeeping has stated that many fancy goldfishes suffer greatly from it.

But what if even well-outcrossed artificial color morphs suffer from invisible but significant pleiotropic effects? Such effects have been documented in melanistic Harmonia lady beetles and a Wikipedia-cited research article on frizzle-feather chickens. And might long-term breeding in commercial facilities cause problems from unconscious artificial selection to occur, such as an evolutionary trend towards lack of brainpower and lethargy-when-not-eating to take advantage of infrequent but heavy feedings? How are we supposed to not worry ourselves to death when many of the rare imports have almost nothing known scientifically about their biology, and so many "human errors" such as artificially-created ecological disasters have been made, apparently with the support of scientists?

Hard facts and extrapolation from zoos, history, etc. are appreciated.




EDIT: I may not be able to post much due to login-related things, so reply accordingly

[Bas Pels]

One thing we all select on, is viability in a tank. After all, a fish which does not accept living in a tank will not survive long, and if others do better, they are the ones that breed.

That might be part of the explanation why F1, F2 are most often easier to breed than wild caught fishes.

I think what you did mostly was pointing out what might need to tolerate in order to survive a tank - the waiting to be fed, the feeding in one go, the fierce competition when fed, the sometimes onnatural place where the food comes from.

But also the often onnaturally stagnant temerature: all day long, all year long the same temperature is in many areas not natural. It is in the Amazon forest, and I think in West Africa - but elsewhere?

The same could be said for water chemisty. In many areas there is a dry season (relatively hard and polluted water) and a wet season (relatively soft and clean water) which also influence the availability of food (unless a toppredator, in the dry season food is scarce)

And than, if you want to breed, and have 1 male and 1 female, they need both to accept the conditions. Larger groops do help, but there could be more aspects.

And yes, if we breed, we might select too. Firstly again on survival, but then, some fishes might be a bit dull - these are culled first. Others might have a different pettern, these could be culled, or considered interesting.

Recently I was given a group of Xiphophorus montezumae (a sworttail from the Rio Panuco system in northern Mexico). Their ancestors were collected some 10 years back,but the line is still healthy. However,they have been selected for black on their body, and are therefore much more colored then the ones I used to have in 2010. I will try to uncolor them

It all happens, willingly or not