I know many people will not like this, but I was getting bored with just 3 fish in my 5 gallon tank. So I went ahead and bought 2 more female guppies yesterday. I now have in my 5 gallon hex 2 male guppies, 2 female guppies and 1 cory. I am soon going to buy a bigger tank. But wanted to take my chances to see is it so bad to have 5 fishes in 5 gallon. I will follow my routine though with water changes etc.