Two ATF of any species kept together with nothing else in the tank is a recipe for disaster.
You need to provide cover for these fish. Most young riparian fish, to include ATF, like to hang out in what fishermen call "riffles"- areas with significant surface disturbance from moderate to heavy flow over a rock or something that breaks up the surface agitation. Combine this with some fake plants and you have a young riparian fish who would feel very safe (this is why I advocate flow in the guide more than the treadmill effect; I need to rewrite that).
Lights aren't particularly important during the day, but I've found that moon lights cut down on nighttime spazzings.
As for cohabbing fish with ATF, I don't recommend it. In the wild, the only species that we have legitimate scientific data to suggest they shoal in the wild are vatf and fatf, and even their shoals break up at sexual maturity with mature fish being quite intolerant of each other. Even in I'm mature fish, they only tolerate like sized fish, a larger fish in the wild will always persecute a smaller one. These guys are ruthless.