Got some new nerite snails last Thursday. Noticed today they hadn't moved in a few days. Picked them up, uhhh... shells, no snails. Pretty sure my 3 krib fry (They're not really fry anymore I guess they're 5 months) ate them. My adult male krib (their father) in my planted tank has done his share of killing with mystery snails. Apparently I have a strain of krib that hates (or really enjoys the taste of) snails. Awesome, and still I have diatoms.