With a Red-tailed Shark and Tiger Barbs you would be on the way to an Aggressive Tank. Are you sure you want to limit yourself to having that many aggressive fish? They do kind of limit the smaller fish when you have quite a few aggressives as the more crowded the aggressive fish are the worse their behavior is.
You will have 55 gallons and Rams and the Red-tail are a good start. Have you considered Rasboras, Danios, or one of the other Barbs ~ there are a lot of species of Barbs not just the Tigers? Some of them are not as aggressive as the Tigers.
Rose
