i just recently got 2 blue gouramis for my 20 gallon tank. already with 2 cherry barbs 3 neon tetras and 2 plecos. now the one gourami has killed all 3 of my neon tetras and now keeps attacking one of the cherry barbs and even the other gourami. it seems to keep nipping the fins all most of my fish until they die. is there any way of lower this gouramis aggression because its harrassing everything it sees. help would be aapreciated.