I have a black trapdoor snail who happily munches his way all through my 20 gal. I had purchased him for my 2 gal. but my betta tried to eat his new housekeeper and kept attacking him. I only purchased the snail a week ago tomorrow and I can see a vast difference with the amount of brown algae on the decs, fake plants, walls, and even the thermometer has been given a going over. I hadn't wanted a boring old snail but I'm delighted with the little fella.
