My sister and I just purchased 2 male bettas. They are both from the same store and were both put into their tanks the same way. My fish is doing fine but her's seems to be swimming errratically. I looks like the fish is twitching. It will dart back and forth across the tank, stop, open its mouth wide, act normal and then start all over again. My mother says its just a happy fish but i think otherwise. Please help me fix my sisters betta.