Fish can be recognized among the various species and varieties, colors, etc.

[Velvetgun]

Sorry for another of my strange questions.
Lately I've been curious about the varieties within a species and their ability to recognize each other.
I love the various species of corydoras, I find them interesting and cute.
However, a question came to mind:
If in an aquarium there are for example 6 corydoras orange Venezuela, 6 corydoras panda, 6 corydoras green neon do they recognize each other? That is, do they move and interact as a sort of single school or do they divide among themselves based on the species?
And in the case of varieties in which albinism has been selected? Does an albino recognize a non-albino?

 

[GaryE]

They recognize the difference, but don't separate from albinos of their own species. We have to stop thinking just with human senses, and living in a visual world. A fish like ones in the Corydoras group doesn't have breeding colours. So I doubt that for them, the eyes are crucial. I confess, I've never looked at a paper analyzing the structure of their eyes. But many fish see ultraviolet, and colour spectrums we can't. Corys also have those super sensitive barbels, and I suspect the chemical communication we call smell has a lot of importance.

We call them "cats" but they may be more like dogs.

There are families of fish that communicate with electrical pulses, and scientists tell the species apart the same way the fish know their own species, by reading the pulses. Each species has its own electrical signals. To our eyes, they all look more or less the same.

The goal of Cory group markings is camouflage against predators, and if they start hanging with other species, someone is going to stick out in the group. Difference is death for "herding" fish when a predator chooses which prey animal to attack. It makes a lot more sense to stick with fish you can easily blend in with.

 

[Velvetgun]

I had published this post in an Italian forum and I read contrasting experiences. Some said that they all went together for example corydoras orange Venezuela and Sterbai, others that saw divisions with detached groups, others that saw a difference between albino and non-albino corydoras aeneus that also seemed to relate to two distinct groups.
I really like what you said and a reflection also comes to me from other worlds
For example in the dog world I have seen in person in litters for example where there are merle and non-merle or red and white puppies (see border, aussie) that the puppies were together by color even before opening their eyes, before ten days of life.
Same thing in my last litter I have two puppies with slightly longer fur, well they are almost always together both before they had their eyes closed and now that they are almost 50 days old.

 

[Magnum Man]

I actually think it depends, with no constant... there must be something, more than looks... granted most of my mixes would be centered around my experience with tetras, both South American, & African... I've found that most often tetras will school with other species, but typically not what humans would expect if they look alike... but I've witnessed a schooling effect ( acceptance ) based not on looks, but something un seen... maybe hormones given off, smell or ???

 

[TwoTankAmin]

One quick observation here. Behavior in the wild v.s. in an aquarium. I have watched different species hang together in a tank. I have never seen a video in the wild of groups mixing. However, my fish knowledge based on what I have seen in my tanks iis one thin but I have never studied fish in the wild. All my experience with wild fish comes from vids, books/papers and from people who have spent time doing research and collecting there.

When was the last time most of us saw 50 or 100 corys all schooling together in a tank?

 

[Magnum Man]

Interestingly in none of those "wild" videos, were the Cory's on sand...

 

[GaryE]

Interestingly in none of those "wild" videos, were the Cory's on sand...

They're migration videos. Corys move fair distances, and feed best in sandy or loamy soils we can't have in tanks. They like to eat invertebrates that live in fine grained substrates, and the mouth adaptations say more than videos.

In many cases, sand is the closest substitute we can come to for the substrates they feed on. Geophagus are found over similar substrates, and they work the soft bottom material (which tends to be sandy) in their own hunt for similar foods. They go around the rocks and pebbles.

When you shoot videos, you need access. With a lot of forest habitats, your only point of access is where a bridge crosses the stream. You can clamber down and set up a camera. But bridges and roads disturb environments - a lot of debris ends up in the water. I saw a lot of streams where 50 feet up or down river from the bridge,you often had soft mud bottomed streams, but under the bridge, you had road gravel and rocks. I hadn't really thought about that until someone pointed it out to me, based on his South American experience. I realized it was exactly what I had seen in my favourite African fishing spots.

A problem with anecdotes about different Corys hanging together is numbers. Keep 3 of each, and they form loose groups. I have one incolicana that runs with other species, as it's alone and I can't get more. Keep 50 of each, and you may see different things. But who has space and money for that?

Many Cory group fish live in one small river and don't encounter other Cory group fish in nature.

 

[Velvetgun]

if you love shooting natural environments where fish live I also recommend him
report south america