How do snails & crabs benefit a FOWLR? I have a 55g with 4 fish, 3 shrimp, a starfish, 4 hoseshoe crabs, 2 margeurite (sp?) snails, and a cerith snail. The crabs & snails are busy! I love watching them. How many should I have for best results?
They along with your other inverts will eat food the fish did not get to and some inverts will eat pest algaes as well. I would like to comment on your 4 horseshoe crabs though. There are 4 different species all getting very very large and do not fare well in home aquariums. They almost never make it to their full sizes of about 12" across and 24" long because their nutritional needs are not met. Small snails like nerites, margaritas and astreas usually don't add much to the bioload so you could have many.
And on the snails it is kind of a matter of how much food (algae) you have in your tank for them to eat. I have 100 gallons of water and about 20 snails now and I feel like they are probably on the hungry side. The astrea snails are good rock cleaners, a few of those would be good to have. The ceriths in my tank work on the sand, glass, and rock. I like them. I had about 10 cool black and white ones hitchhike in on my rock. The banded trochus snails I found are some of my favorites. They only come out after dark and work their shells off cleaning. Like Heather said they don't add much to the bioload. I would just add a few astreas and a couple more ceriths and see how things go. You can add more in a month if you need them.
