Hi I'm a bit of a rookie at reefing!! Had my 20g nano set up for about 2 months and thinking about stocking with fish, Have already got 3 H crabs and 3 turbo snails, Plus loads of other critters that have come in on the LR!! Not sure how many fish I can get?? Was thinking about getting One black and white clown and One Tue perc clown!! Do you think they will pair up??