I try to drain my stuff dry, especially on hot summer days. I have crawdads crawl out of the no O2 puddles. Between the water temp and lack of dissolved O2 nothing survives. Stupid bullheads wull bury themselves in wet mud and live. Somehow, someway it sounds like you got a load of bullheads but unless are fry they are fairly easy to distinguish from each other. What a bummer. If you can't or don't want to sun bake those guys there are numerous products you can use. Lime is one. Anything alkaline or acidic cna knock the ph so far out nothing can survive. Rotenone, oak bark, electroshock, black plastic. I have never stocked a bullhead.
