How many in a 40 gallon? I know with African cichlids. to keep the agression down. you can overstock the tank a little bit.. but since Firemouths grow 6-7", is that still how people do it? Or any type of NW cichlid that grows bigger. Like Jack Dempseys.. don't they grow up to 10" ? how many in a 40 gallon? And since the number would be significantly smaller than say africians that only grow 3-4"... how do you keep agression down in the tank?