116% means that it is over-stocked. Guppies are not good because their tails are tempting for bettas. Tetras should be in schools of probably at least 6. In a 5.5 there really is not enough physical room for the betta, or other fish, to get away from each other. Most of the other fish are schooling fish and should be in larger groups then what would fit in the tank. I'd only recommend african dwarf frogs, snails, or shrimp.