Fish's stomach is only as big as its eye?

[scavenger]

Many fish sites I've been to tell newbies that fish should be only fed a little because its stomach is only the size of its eye. Now, I'm no expert on fish anatomy (in fact only a beginner that has never kept anything beyond tetras, minnows and danios), but common sense tells me otherwise. That would be WAY too small a size. I mean a big fish that's 3 feet long can't possibly have a stomach, say only an inch or so in diameter, right? Someone who follows this advice would probably be grossly underfeeding their fish, right?

Does anyone have anything to say about this?

 

[Kasakato]

I think that rule works for most fish. Human hearts are only the size of your fist, and your brain is your two fists put together. Not big at all.

 

[scavenger]

It seems that the rule is only true for very small fish whose eyes are larger in proportion to its body;it seems ridiculous to compare this rule to big fish (if this were true, then a predatory fish could never swallow anything larger than its eye). Even more ridiculous when compared to wild fish like the great white shark thats 15 feet or so in length and eyes a few inches in length. There would be no shark attacks if this were true because the shark would only barely be able to swallow and digest a sardine!

One only has to look at photos of fish to see how odd this "fact" would be.

 

[Kasakato]

Ya exactly. Maybe someone knows the truth behind this?

 

[RTR]

But then, a lot of us do not keep Great White Sharks. Since many fish in captivity die directly or indirectly from overfeeding, that 'rule of thumb' is far better than most IMHO & IME. Fish in captivity dying from underfeeding are quite rare, and generally because the keeper does not know what types of food the fish requires.

 

[Kasakato]

Good point! So its good as a very general rule, and nothing else.

 

[scavenger]

But then, a lot of us do not keep Great White Sharks.

But a lot of aquarists (not me though, at least not yet) keep reasonably large predatory fish such as arowanas, large cichlids, catfish etc.. Would the rule apply then? It seems these fish can swallow and stomach much more than an eye-sized morsel of food.

 

[troy272]

i do know its true for tetras.

 

[phanmc]

Like the 1inch per gallon rule, its not true across the boards and only applies to small fishes. However, since the majority of aquariums houses small fishes, its an effective guideline for most to not overfeed their fishes.

These "rules" are just meant to be guidelines for beginners and are not meant to be the definitive rule.

 

[zacdl]

As someone who has actually seen the inside of a fish, and all the internal organs... This is false.

Their stomach is much larger than their eye.