I have a 27 gallon. The filter overturns 10x . I have : I fire mouth, 1 red zebra, 2 jewel chilcid, 1 opaline gorami. All is well besides the fire mouth..... The gorami is the head of the tank by no doubt, no one has ever stood up to him. Second on the food chain, the zebra. He chases the jewels around a bit but never picks at them, its harmless. Then, the jewels they are both female, and very pretty. They never bother anyone. Last, the fire mouth. All he dose is hide in the caves. I chose the least aggressive one at the store. Should I re-turn him for a more rambunctious/ active one? Thank you!