i have 9 .5"-1"tigers... consisting of NGT, NTT, IT, and ST. the chase each other occasionally but nothing too serious. o yeah, they are all in a 20 gallon tank with a 4" jardini, regular pleco, and an angelfish. yes i know its over crowded, but my 50 gallon tank is over crowded too and im waiting for my 170 thats coming in tomorrow