I don't know the data on your tank, but the territorial issue Lunar mentions is certainly correct. Gourami males of any species are highly territorial, very much like male cichlids, and the tank size must be sufficient for the species and numbers. Different species of gourami in the same tank is not usually good, especially with the larger species as we have here (Pearl and Blue).
Another aspect is the size of the tank, if small for the number of fish, can inhibit natural behaviours in fish initially, so things may appear to be smooth. But at some point this stresses the fish and then it can be even worse.
Byron.