The garlic isn't going to affect anything...get some researching going on vice posting at late hours to up that post count....if you are that worried about it, dilute the prime with an equal amount of water and dose like normal..heck, I dose Seachem's Garlic Guard straight to the tank vice soaking food in it....
If it is better for a feeder fish to die, l125, then I guess we all should stop fishless cycling then...