They will not fight. There is lots of room, I have seen lots of tanks that were over crowed n still they didn't fight. You're possibly thinking about Betas. One male Beta will add an awesome splash of color, I've seen it work just fine in multiple tanks. Pet stores keep LOTS of males together without them fighting, The only way I could see there being an issue is if you reversed the ratio n had 3males to 1 female. I could see that as n issue. But so long as there are lots of females to go around, the men share just fine.

Just remember, male fish are like wh0res, they like a variety of women at there disposal.

The male fish views his females as 'Lays' chips, can't have just one!