I would never but a fish just to solve a problem with my tank. laoches for snails, plecos for algae, just doesnt make sence IMO. Then if you have no more snails, or no more algae, you have to suplament their diet. There are ways of getting rid of snails without buying a fish(especially a tankbuster like Clown loaches.) I personally like snails in my tanks, and regulate thier population through good tank maintenance. If you keep your nitrates down, you will have less algae. Less algae means less food for the snails. This keeps them in small populations to be benificial to your tank. (mts are great at turning over your substrate, eliminating stagnant pockets of waste. )
If you have a population explosion, take a small plate or bowl, rinse with dechlorinated water to remove any soap residue, and place it in your tank. Use a piece of letuce, or cucumber, zuchini, any green veggy, and put it on the plate/bowl. you may have to use something to weigh it down. Overnight, the snails will come out to eat it. When you first wake up in the AM, go ant pull the plate/bowl out along with the snails. Dispose of them properly, DO NOT FLUSH, DO NOT RELEASE INTO THE WILD! I would recomend placing them in a bag in the freezer for a day to kill them, then throw in the trash. This will not get rid of the entire population, but along with regular maintanance, it will keep them to a small benificial populus.
A side note, I am not familier with every species out there, but of the hermaphorditic pseudopods I know, they need 2 to tango. This means that while they carry both sex organs, they still require another snail(or slug) to mate. Each one impregnates the other. This is to ensure genetic diversity.