HI All. Thank you for letting me join your forum. I am quite new to fishkeeping. I bought a second hand 180 litre (79 us gallon) community tank complete with fish. I've had them 6 month and all has been well until the last few weeks. I (did) have 3 tiger barbs. One of them had tail and dorsal fins nipped badly. I removed the two aggressors to a 57 litre tank. One of them was terrified. Pinned up against the glass and was threatened by the other every time it moved. I put it back into the main tank. It attacked the other tiger that was there and killed it. I now have one tiger in the main tank that appears to have settled down. And a lone tiger barb in the 57 litre tank, which I know is not good for a schooling fish. I don't really want to get a school of tiger barbs in case the aggression continues. And the tiger in my main tank is stopping me stocking guppies/frilly fish. Any suggestions?