my brother ahs a 15gallon tank. it has 2 baby irredecent shars, and 1 baby bala shark. there like 1 inch each. and 2 of those small mollies, and 1 little guppy. he wants an angel fish but i dont think it would be good for the other fish in there as their community fish. what do u all say? my aunt said that they can be mean because she had some that were mean.