I have two peppermint shrimp in a small tank on my desk. It is a 2 1/2 gallon tank with three reef rocks and a Seachen Tidal 35 filter/Seachem Matrix Carbon and Poly-Fil. Can I add a few different species shrimp into this tank? Also how would a few emerald crabs and a starfish work? Would the shrimps eat each other? Would the shrimps eat a small chocolate chip starfish? Thanks all