Mixing Male Gouramis?

Hello all,

I have a tank with 2 Male Dwarf Gouramis and 4 Serpea Tetras. The tank has
two large live plants and plenty of large rocks to hide out under. The two
male gouramis are constantly fighting, but they seem pretty healthy so I'm
not too worried about them.

My question to everyone is: Can I add other male gouramis (different
varieties) to this tank, or will all the gouramis fight? I would like to
get a blue gourami and a gold gourami, but I'm worried that they will
constantly fight and eventually die.

Thanks,

-David