there might be some tension in the shoal when i had my 3 super red bellys in my 55g i had a runt and the other 2 would not let him eat and things like that....they never came out always hid never let me watch them eat.....well after a fungus attack killed the other 2 my runt and gained a ton of weight and is fatter and happier than ever.....he also comes out so much more than any of the 3 ever did.....i guess he thinks he's the king of his tank and he likes it that way