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My boss told me the LFS told her that eat fishes stomach size could be judged by the size of the fish's eye. (same size)

Is that true ??

:88)

thats what i heard, but their stomach can also strech, just like ours

It's an approximation, but yes, that's a general guideline.

~Meow. Thus spoke the cat.~

That's absolutely ridiculous.:%) It may be true for some fish or even a good number of them, but in any one feeding I always feed my fish more than the size of their eyeball. And they always eat it too, which would be somewhat impossible if their stomachs were only so large.

Then again, I don't keep those little tetras and stuff. In fact, all of my fish are predatory or grazers, which tend to have large digestive tracts either for holding a lot of food or for constant digestion.:%)

Last edited by Shinigami at 02-May-2005 19:20

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The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.

I think what is being suggested is that for fishes that have attained full adult size, there is a proportionality relationship between eyeball size and stomach size. In other words, if E is the volume occupied by the eyeball (which thanks to its symmetrical shape is related to the diameter) and S is the stomach volume, then E = kS, where k is a multiplicative constant of proportionality that is fairly uniform across different species.

However, I can think of one immediate exception. This fish is known as Chiasmodon niger, the Black Swallower. This is a deep-sea abyssal fish (found at sea depths beyond 3,000 metres) and at those depths, food is scarce. So it has adapted a unique predatory lifestyle which enables it to swallow a fish twice its own size. It has a highly elastic alimentary canal for the purpose. in the case of this fish, any such relationship completely falls apart.

Plus, if any such relationship truly existed, I think that anatomical textbooks would have commented on this, and i have yet to see any such comment in the (admittedly few) books I've read on the subject. After all, anatomists have used proportionality ratios between the sizes of certain key anatomical features as a classification tool for about 250 years in all manner of vertebrates, so I think this one would have turned up in the textbooks by now.



Last edited by Calilasseia at 02-May-2005 22:55

Panda Catfish fan and keeper/breeder since Christmas 2002

I think puffers would also be a noteworthy exception. Their stomachs are quite elastic and they can easily double in size during a big meal.

Definately not true for catfish and cichlids. My texas can easily eat more than what his eye size is. The same is with my syno. multi.

My corys definetly have stomachs bigger than there eyeballs and my otos have stomachs almost as big as there head.

Think about how much eyeBALL there is that you don't see.

You also have to keep in mind that stomachs are designed to stretch to a certain degree, and that food moves through the digestive tract of a fish much faster than that of a human.



Its a reasonable rule of thumb for small to medium tropicals, but once you get over that size, you are probably going to find that the relationship between the two organs is not so similar.

Last edited by Callatya at 03-May-2005 03:04

For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

so this isnt true.. black moors..bubble eyes..

{dud}

Last edited by dude_dude at 03-May-2005 05:52