My 8 year old son has a 55 gallon freshwater tank (two weeks old) with community fish. 2 male mollies, 2 male guppies, 1 striped peacock eel, 1 boseman's rainbowfish, 1 new guinea rainbowfish, 1 threadfin rainbowfish, 1 red fin shark and 7 zebra dannio's. Two rock formations, two live plants and...