[LiVEWiRE]

I added my cleaning crew Snail, Crabs, Hermits, Etc first before I added any fish. The fish were the last thing I added. You can get some now most LFS sell snails in sets of 5. Unless you are getting fancy ones. But you don't say how big your tank is. So I would start out with 5 and see how they do if they are doing good and you are still have issues with tank maintenance then next week add 5 more and so on. I have been told 1 snail and hermit per gallon of water but I believe in my own opinion thats a bit much. I would go maybe 1 per 2 gallons myself. You will also continue added them even when your tank has matured that is if you have hermits. Hermits need a new shell as they grow so if you dont have different sized shells in your tank for them to move into, They will kill your snails and take their shell. It will happen even if you have some shells in there for them but no where as much as if you did not. I have seen a hermit kill a snail take its shell not like it and go back to its original shell. But yes you can add snails. Just take it slow. I let my tank cycle for 2 months before I added any animals to it. But you have the fish in there already. Just go slow from here and take your time. It will pay off in the end.