I am currently in the market for another central american tank to go along with the collection of others. I have room for a tank no more than four foot long. I am looking to house a pair of something like red devils,trimac, midas or something about that size.I know these fish establish their territories horizontally and not so much vertically,I was looking at possibly a 75 or 90g tank since the footprint is the same.Logically the 90 would be the best bet for a pair of fish, but how much difference would that 4 extra inches of height over a 75g make.I'm even thinking real hard about a 120g.what experience do you guys have with a 75 or 90 ( I think I know the answer,but would like some "expert" input) thanks