Angel in a 20 gallon

[Tampa]

In one of my tanks, a 20 gallon high I have a good sized angel fish. It's body is larger than a silver $ coin. Only other fish in there is a zebra danio and a bristle nose catfish. All of the (fake) plants are off to one side. What fish can I add to the tank to "liven" it up?

Thanks for any suggestions

[Rbishop]

While there are plenty of fish to "liven" it up, such as tetras and cory, I would first advise finding a new home for the angel and BN.

[Lupin]

A long tank is better for the danios. They should be kept in groups, not singly.