I'm watching my little 4.5 inch green terror female own my 60 gallon right now.I think she has eggs hidden somewhere in the tank.She has a 4.5 inch grammode,a 5inch female trimac,and two 3 inch flowerhorns on the run right now.I think an umbee would be running for its life in a 300 gallon tank at this point.Just joking.A green terror could work though.At pet kingdom in san diego they have a 10 inch terror in their pond and I want it bad! It's so beautiful!