We returned one fateful night to find a grisly murder had taken place. Dad fish hung perpendicular by his tail from the filter. His scales were all askew and his fins were stripped bare to the bone.
The baby fish kept a wide berth from the parent tank, having witnessed far too much violence for their young fish eyes to bear. We were all shocked and hoped in vain that he was still alive. My mother poked him with a stick, and having been separated momentarily from the pull of the filter, he gently glided to the bottom of the tank and lay motionless on his side.
It was a low moment even for our frequently dramatic fish community. We scooped out the Dad fish and, after a short deliberation, the mother fish was scooped out too. Dad fish was shipped off for a one-bite burial in my sister's turtle tank, and the mother fish was taken to the pet store and exchanged for a new, less aggressive fish.
Lo and behold, the new arrival, a pretty silver and teal Platy fish appears to be pregnant. So one mother was replaced with another.