Fish and schooling, how do they differentiate from each other?

[HenryC]

I just recently saw a post regarding a lamb chop rasbora not swimming around with the group of harlequins in the same tank. I find it fascinating how fish won't school with others, even if they're nearly identical, for example neons and cardinals. You see the example everywhere! Even if they're borderline the same, they won't school if they're not the same species.

I've always wondered what are the mechanisms they use to differentiate themselves from other, very similar species. It has to be with pattern recognition for sure right? Not sure if there are papers about this, but my theory is that they have evolved to develop and recognize unique patterns and colors, that's why you see lots of different patterns, and sometimes unusual ones, like the silver tips on silvertip tetras, the full red line on cardinals VS. the half red line on neons, the red spots on bleeding heart tetra VS the black one on serpae, rummynose's characteristic red snout and checkered tail, black neon's white and black lines, etc. They're programmed to scan for these cues that tell them they're good to group and mate with them.



Someone once told me pheromones had to be responsible as well. Do you think that's the case?

What do you think about it?

Edited June 25, 2021 by HenryC

[xXInkedPhoenixX]

I think we don't give animals enough credit. Maybe it's more simplistic but I think fish can easily recognize same from not. Just like some of us can recognize a different year of car just because of the slight redesign in a tail light from one year to the next. In fact I think animals are better at it, because they know when there's a sick fish amongst them even before we do sometimes. I guess I prefer to have a sense of wonder about nature instead of trying to put a scientific bent on it- but that's just me. A more mechanical mind definitely wonders what it is that makes them tick. 

I think schooling is a facinating thing especially from an evolutionary/safety standpoint- and it's amazing the difference from fish to fish. I watch my 10 Harlequin Rasboras- pretty much ALWAYS in some formation or another- even facing the same direction- ALWAYS together. Then I look in the tank next to them with my Black Neons- they group up when I come near but then disperse and do their own things otherwise. 

[lefty o]

im sure there are multiple minute reasons, but fish tend to have pretty good eye's for color. my guess is they can see the difference. as with most animals/people/fish etc, they tend to gravitate towards their own kind, as similarity is comfortable.

[tonyjuliano]

On 6/24/2021 at 8:39 PM, HenryC said:

I've always wondered what are the mechanisms they use to differentiate themselves from other, very similar species. It has to be with pattern recognition for sure right?

The most current prevalent scientific theory is that it comes down to smell.

To identify another of its kind visually, a fish would have to be aware of what it’s own image is, which we know is impossible.

They can, however, smell themselves, and can use this to identify others of their own kind.

Fish have an amazing sense of smell—much better than a human's—and most, if not all, other animals.