Hi, I keep reading how you should put at least 6 fish together if they are a schooling type fish. However, I've noticed that a lot of people don't actually do that. I have noticed where for example some people may have 2 neon tetras, then also they will have 2 of another type of tetra and 2 of another type. Is it okay to do that or are we really suppose to keep it to 6 of the actual one type of fish?