So far in my tank I had this in order...Stars and Strips Puffer, Snow Flake Eel, Porcupine Puffer, Niger Trigger, Yellow Headed Eel (about a 20 inches I was worried about him but hes harmless) then I saw a small Clown for 35$ about 2 inches all my other fish are med side 4-6 inches. My puffers tend to stay by each other and both triggers accually sleep together. The Yellow Eel and the Snow Flake sleep with each other well. When feeding my Yellow Headed Eel will come out and look like hes going to attack for food but once he gets the smell of the fish he backs up. So for no aggression what so ever. My Larger Niger accually helps my clown get food because of my puffer likes to eat every thing in the tank... So we will see soon once i get my queen trigger if them will all get along but from what I have learned add the more aggressive trigger last and slightly smaller... Mine tends to be shy and harmless