Since getting my Assassins a couple years ago, I don't have as many snails as I once did, so my use of them as fish food has declined a bit. In times past, I would crush them against the glass daily, whenever one happened to venture too close to the surface, and most fish learned to come running; the bits were quickly devoured before they hit bottom. I still harvest a bunch when doing actual tank maintenance and feed them to my turtle; it's a dietary supplement that allows him to hunt them down and devour them over a period of time. A quiet reading session in the den is often punctuated by the sudden crunching of another hapless snail being found and eaten. Music to my ears! 
I started doing this back in the 70's; if there were any negative effects I would probably have noticed them by now.
I started doing this back in the 70's; if there were any negative effects I would probably have noticed them by now.
