Red Cherry Shrimp Help!!?

I bought 18 Juvi RCS off ebay. In my tank I have about 10 Neon Tetras, 5 glo fish, 3 albino cory's, 2 Glo Light Tetras ( have to get more I know!), and a male betta. I put 18 RCS in the tank and saw the Betta attack and eat them before I could get them all out. I have got rid of the betta now and have 6 RCS left. I had some Ghost shrimp but im sure the African Dwarf frog finished them off. I got rid of the frog since then. I have alot of water wisteria, driftwood and Vals. do they multiply fast? I have a 46 gallon tank with 2 canister filters, can I add any more fish to the tank....