They're not too bad it depends on the individual fish, I had my 2 pairs of golds in one tank and they were ok, the first pair layed and both of them chased both members of the other pair, but when the second pair went to lay all hell broke loose and I had to seperate them.. You could get away with 2 pairs in a 3ft tank, but if you wanted a nice display then stock it with a heap of males and it will be awesome