Well, I would certainly recommend clown loaches as they love 'em, but I think that might create an overstocking problem for you (depending upon how many you have of each fish you list). Your next best option is to sink a large romaine lettuce leaf in the tank, and in the morning you should have a giant crop of them clustered upon this leaf. You remove the leaf, remove the snails. I rubber band them to a rock or even to a plastic utensil and dig the utensil into the gravel, if you don't have a veggie clip that suctions to the glass. I think this is likely the best method, as I would hate to see you use some sort of chemical to get rid of them. You can also put the leaf of lettuce (zucchini, cucumber, etc) into a glass jar and remove the jar.
Another factor here is that you may be overfeeding if there is enough food to support these snails. If you cut back on your feeding, skipping a day a week, even, you might find that the snails reduce in number. Many believe that starving them out is the best way to go. They don't have to be the scourge you imagine! A couple of snails is a nice addition, and as adults they are as interesting to watch as the fish!