When a tank mate is nipping their fins they move away.
When something is irritating them like ph or disease they try to rub it off.
When they are injured they favor and protect it if they can.
So how is it they can't feel pain?
They don't seem to like getting parts chewed off.
Most likely these studies show the testers incompetence and bias.
I once bought $80 worth of various small fish to feed to an Oscar. Just to see what they would do.
Of course the first to be eaten from each batch went down easy. Because they had never seen a predator before. But the others see what happens and learn from it. They run and hide as best they can. And the longer they live the better they get at surviving. For a while.
One Fat Head lived for months by tailgating the 10 inch Oscar. He knew that if he stayed at the tail, he would be keep out of the mouth. (he only died when I moved and they all went in the dumpster)
From what I have seen these little brains are allot smarter than we give credit.
Even things like Ghost Shrimp and various snails show obvious intelligence if you take the time to watch what they are doing.
I still remember the last Neon Tetra hiding under cover, obviously terrified. And I feel a bit guilty at putting them in a situation where they have no chance. (strange, because I'm generally an a**hole) No this is not exactly like what happens in nature.They can't run very far in an aquarium.
Regardless, I feed Convicts to my Oscar and Jag.
Bad for the Convict. Good for the Oscar.
And dying fast in my tank might be better than dying slow in someone else's tank.
I just don't put too many in at once so they don't know what's going to happen.
And keep them small so they go down in one gulp.
PS Goldfish are super dumb.
