This is what I was told, based on the mature size of your fish, it is best to aim for 1 inch per 3 gallons with a max of 1 inch per 2 gallon. This is just an estimate. So based on that, the Clowns and Coral Beauty will each be about 4 in. and the blenny will be 5 in, plus 6 in. for the Bicolor. So about 35 inches of mature fish. How about a bigger tank?