This package is comprised of cleaner selected for their abilities to consume detritus, scavenge, and stir the sand. It is perfect for 50 gallon reef aquariums. it contains 1 Sand Sifting Star, 1 Tigertail Cucumber, 20 Super Tongan Nassarius Snails, 20 Cerith Snails, and 10 Bumble Bee Snails. For larger aquariums simply order multiple quantities of this package accordingly.