Anything from 1 to 3 depending on how large they grow. They are hybrids so they can grow from 6 to 10 inches, if they are 6 inches I say 3 if you get an 8 to 10 incher you will only have room for 1. I have seen an 8 inch female that was literally 4 inches wide it looked like a swimming football and that would make your 75 look tiny. I currently have 1 in my 75 until I get an idea on size or get a larger tank.