Some years ago, we kept tropical fish, one of which was a male Betta splendens, commonly known as a Siamese fighting fish. While only the males fight each other, they can sometimes be aggressive towards other species.
Hah! Not this boy. He was the biggest wimp I ever knew and, if we had not fed him apart from the others, would probably have starved to death!
But he was handsome, in his peacock blue and silver finery.