It would be hard to find a carnivorous fish that would coexist well with the gouramis. The fish I mentioned would be better suited for a species tank, with the exception of the halfbeaks. Some halfbeak species are suitable for mixed species tanks, but keeping them with gouramis isn't a good idea because they both like having a large surface territory. I kept my halfbeaks with dwarf gouramis short-term and they did fine, but it wouldn't be a good long-term situation.