Hello, My tank is a 20 gallon long. I have 7 Neon Tetras but plan on 3 more for a total of 10. I have 2 Agassizi Cory Cats. As for the Agassizi's, do they like and feel safe with any other Cories? Right now they are not very active and I was going to get one or two more. I would like a couple more fish maybe 1 1/2 - 2 inches that are very active and bright in color like a red or yellow or orange? Do I need shrimp or snails? Thanks for any and all advice!