I have two male dwarf gouramis and one is much more aggressive than the other. The one swims around the whole tank and keeps the other one pinned in a corner or stuck in a plant. I am very seriously considering asking my
LFS if they will take one back (even for free). The quiet one doesn't even feed with the other fish, but he must be eating something (like my plants!) because I see him poop. Now the aggressive one is starting to nip at his tail -- somebody has to go.
It's a 20 gal. tank so maybe it is just too small for two dwarfs.