Hi I have lost a black guppy and a black & white mollie within the last month. Found my Mollie on floor of tank just now. I normally feed them flake food, but also have just brought a clown loach so have introduced tetra wafers - so put 3 wafers in last night as well as flakes for my other fish which include 3 guppies surviving 2 black widow tetras and 2 red cardinals which are all still hardy. I have also just introduced an air pump. Do you think I am doing something wrong. please help!!