I have black khuli loaches and they dont eat snails at all, although i am not certain on other varietys of khuli loaches. Do you have a snail infestation problem and how many gallons is your tank and its fish stocking? There are some good snail eating fish out there but many grow too big for the average tank.
Most snail infestation problems are caused by over feeding your fish and/or not cleaning the subtrate enough, do you know what type of snails you have?