Originally Posted by russp
Has anyone else found it better to keep an odd number of similar fish? It seems when ever I have even numbers of fish, they are more shy but with odd numbers, they are more active. Fact or am I seeing a behavior that isn't there?
Meant this to be a new question. not a reply
Oddly enough, I have heard that schooling fish like tetra look best if kept in odd groups. Doesn't really answer your question, but it's food for thought.
About the water level, I think it depends on a lot of things. Do you have fish that need a high level of oxygen like goldfish and hillstream loach? Do you have fish that don't like current such as Betta splendens and gourami? During the summer I lower my water level about a centimeter to allow a little more gas exchange in my goldfish tank, but I also have a tank with fish that like still water. In that tank I make sure the water level is high and the filter flow is baffled.