My girlfriend has a 20g tank with some platies and swordtails. Her tank is clean, except for a few areas where algae builds up. Anyhow,she wants a pleco and I was wondering what is the easiest and most hardy pleco for her size tank. I heard bristlenose plecos are fairly hardy and they have one at the LFS. They are asking $7 and its about two inches long right now. I just want to get her something that is going to be very hardy! Much thanks!!!