I think the only ones that could of fought back are my 3 bluegills, my brown bullhead, or my smallmouth bass. None of them are necessarily full on aggressive to the other fish. The longear is the dominate fish and might have cut himself on some driftwood I guess or from the bullhead. My tank is warmer than usual at around 80F, but is usually 78F or below. I have 2 filters for the tank. I have java ferns, jungle vallis, hornwort anacharis, java moss, amazon sword, and a giant hairgrass. The PH I try to keep around 7.0, but has been in the 6 range lately. I do have other fish but they are not really defensive to the longear. Let me know if you need anymore info.