It's the goonch, Al. I witness mine did to the peacock bass just the past Monday, and it totally shocked me. 3 peacock bass were killed when I first moved them into my 600, but I never suspected the goonch. I thought it was either the rtgg or the frt. The goonch stayed idle against the front wall of the tank, vertically, head up. When the pbass swam pass it, it darted up so fast, grabbed the pbass side way, and swam to the back corner of the tank in a hurry. Fortunately, the bass is big and still strong to able to get lose when the goonch tried to turn it so that it can swallow the bass from the head. These two goonch I have, have been grown up with mainly pellets from the previous owner, until came in my care, then they get chopped mackerel/fish alternately with pellets. I hardly suspect them, because when I fed my aimara with whole dead mahseer in the past, the goonch didn't join the feeding like other fish (apurensis, aul). I was amazed with the way it hunts, even better than the way my bichirs hunted the ATF, when I introduced the ATF into the bichirs tank. New Monster learning everyday!