i have a 50 gallon aquaruim(36x18x18) thats been up and running for around 3 months. right now i have about 25 lbs of live rock that I keep adding to as money permits. It is stocked with 2 young percula?? clowns and 1 coral beauty dwarf angel. acleaner shrimp and 2 small hermits. how many fish can i add and what kind can i add?? I would really like to add another dwarf angel or a tang if possible or what else???