Neon Tetra Question

a little schooling

Huddling from fright isn't the same reaction as schooling. You can call it "shoaling" to distinguish them. Clown Loaches jammed behind the filter intake in the dealer's empty tank.

Two schools in a confined space is like two classes that let out at the same time. Fish begin to have a recognizable schooling reaction when you have a couple of dozen alone together, in a tank that's three times as long as the average length of the school. If you aren't seeing coordinated swimming movements, you aren't seeing a school.
 
Have to diagree with Rocketman a bit. Cardinals do better at warmer temps -- say 79 to 83 -- which is why you see them so often with discus. Neons thrive better at lower temps, 72 degrees or so. I wouldn't mix them...

Val
 
The Amazon is a big river and even bigger when you look at the whole basin, with all the tributaries, etc.: water conditions and temps vary throughout. A given fish may be widespread or adapted to narrow ranges and specific local conditions, temps.

Look at the Mississippi, add on the Ohio and Missouri and all the rest. Its a similar sort of scale, if not quite as tropical. Big and extremely varied.
 
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