They do recognize which fish is "their own." I believe if you keep two of each of those in the same tank you will find that each pair will tend to stay with its partner and not the other tetras. I say pick one and build the school. It will look nicer that way and the fish will be happier.
When we kept the smaller Tetras, we had a school made up of Neons, Cardinals, Black Neons and Glowfish that lived quite happily together until we lost them to a Fungus outbreak.. it's doable if you get maybe two of each I'm thinking.
i have white and black skirt tetras that swim together..they are basically the same fish, just different in color. I love the look of a large shoal of 1 type though...like 20 neon tetras are beautiful! I have community tanks, but would like to have a few more tanks that are just 1 species only.
Different fish will ultimately swim together at times (there are only so many places to go in a tank), but with that said, if you want to provide the fish with the best environment that you can for it to thrive you should really keep no less than six (more is always preferable) of a schooling fish.
I agree. I have tetras, love them. The only ones who I find will somewhat school together are my serpae and bleeding hearts. I think because their body types are alike, they will school at times together. 6 is a great number for a school. I have 4 Bleeding Hearts and 4 Serpae, I am trying to get 2 more each but my lfs has not had any!!!!!!! Bummer!
Schooling fish like Raspboras(Harlequins come to mind) that have a pecking order within the school, may thrive in groups of six and more.. when it comes to Tetras however, Cardinals are just as happy schooling with Neons (they are the same color except Cardinals have a longer red stripe), and the two mix comfortably with Black Neons.. this observation was made with a community tank I once had, also at several LFS that carry a wide variety of Tetras and house them together.. I've seen enough exceptions to the rules of fish-keeping to know nothing is written in stone, and the schooling rule is definitely full of it's own exceptions, its why Loaches sometimes school with Cories (another observation made with the first pair of Loaches I had) and different types of Tetras can and will school comfortably and do quite well together.
I have 2 differnt schools... 9 neons in one and 10 serpae in the other. They both school well, but almost never together. I assume because they're not even close as far as body types. However, it is fun to see 2 different schools wandering around the tank
I suppose it just depends on the fish, some will school with others, some won't. I just got some black neon tetras and they school with the Pristella and Glowlight tetras, but one day they'll be with one species, the next with the other. Yet the Pristella tetras won't school with the glowlights. Other days the black neons will be by themselves. Just depends on the fish.