I have just the two cleaner shrimps and around 15-20 red legged hermits but i have lost track how many i have actually put in. I see all the hermits daily and i also have alot of turbo snails that have never been affected by the hitchiker crabs. Only snails i have ever lost were due to my boxfish but that fish is my pride and joy so he can eat whatever he wants. The boxfish can also eat the hitchiker crabs but they are mainly nocturnal so i don't think he ever gets a chance.