The Dwarf Cerith Snail (Cerithiidae sp.). The dwarf cerith snails are approximately a half inch. Yes they are small but they clean up in small place other cleaners can not reach. ON average about 4 snails per gallon is suggested depending on the cleaners in your tank.They eat all types of algae as well as cyanobacteria, detritus and diatoms. A lid is suggested if you get these species because they can crawl out of your aquarium. They are nocturnal and are very hardy. During acclimation drip them slow although they are very hardy they are sensitive to fast changes of salinity and pH. Make sure that you have a lid on your tank before you order those snails because they can crawl out of your tank. Keep in mind that you want those snails in higher quantities of at least 4 per gallon depending on whatever other snails you have in your tank.