How do you tell gender of a white gouramis kissing fish?

There are no kissing fish that are Gourami. The fish commonly called kissing Gouramis are actually Thick Lipped Gourami.

Kissing gourami or Thick-lipped gourami are not gourami at all. They are actually members of the family Helostomatidae, which also includes the chocolate gourami and licorice gourami.

Kissing fish don't kiss, their lips are actually fused together, as are the lips of many species of fish. This fused mouth gives them the appearance of kissing. And these fish don't only kiss other fish of their own species, they may "kiss" objects in the aquarium as well.

To sex kissing gourami:

Males

-Larger than females

-Brighter colors

-Longer fins

-A small bump on their forehead

-More territorial and aggressive towards other males

Females

-Smaller than males

-Duller colors

-Shorter fins

-No bump on their forehead

-Less territorial and aggressive