I have a 55 gallon tank, with sand substrate, Currently I have 2 angels, 1 male betta, 1 rainbow shark, 1 guppy ( The rest died somehow) 1 danio ( same as guppy), 1 platy (my tank doesnt like multiples of little fish.) 4 australian rainbows and 1 gourami. So I have alot of room to stock, but my...