+1 Kyle Your tank is just too small for the dottyback even if he's little now he'll grow and believe me I have one and they are very territorial fish. He was my first fish addition to the tank (a rookie mistake I know now), and he has claim all the tank for himself. They like to swim a lot and will chase any other fish or shrimp, they need a lot of space to be happy. If your tank was bigger I will recommend you adding some black clownfish. And also, dottybacks will eat shrimp because they are their natural prey, you can always add one, but the risk will be there.
By the other hand, they are definitely great fish. I love mine even when he becomes a pain on the neck every time I add something to my tank. Hope yours do well too, they are very hardy fish.
Good luck! :)