The are mean as hell. The male would kill the female in no time with out a divider. They had just began to spawn. When they finish the clate that is oround 12" x 12" will be covered when finished, so I did not want to get 2 close, I also had another pare of rare fish getting ready to spawn next to them. I cleaned the frount last week and only do so to see the fish. I do a 75% water change each week and that is it. The bang the glass less if the green grows.