I have two bombina, a large light green male named Kermit and a darker smaller male named Scooter. Recently I bought a light brown European male which I named Copper and a smaller female.
Copper is roughly the same size as Scooter but he tackles on top of him and sometimes pushes him under water doing this.

Is there much of a way to get around this besides separation? Anything I can put in there or do?