What size is the tank, and how many gouramis and other fish do you have in there? I see some plants - how densely planted are you? (By that, I mean how much floor space of the tank in a percentage number?)
The blue one looks like Trichogaster trichopterus, an opaline, to me, which can get up to 5" long, at a minimum. I don't know if your gold one is the same, but if so, you already have 2 fish that I wouldn't put in anything but a highly aquascaped (plants and rocks) tank of at least 30 gallons.
Males can be very aggressive. Most of the textbooks and websites say they will be aggressive toward other males of their species, but they can show aggression toward females also.