Woke up for work this morning and was greeted to a rather morbid sight. We keep Malawi Cichlids in a four foot aquarium. Yesterday, the fish were somewhat listless, going to the top of the tank for air, and not really feeding. The spraybar which sprays water into the tank had fallen slightly and so we raised it again so the water circulates properly for oxygen. The fish seemed to perk up. This morning though, I awoke to the sight of them all being dead :cry: well, all except one of the catfish and one of the main fishes. That is, by my estimates, around 40-50 fish dead, all pretty sizable, mature fish. The spraybar had fallen into the water, but the temperature was alright and the filter was still working. My theory is that the fish were starved of oxygen because of this, and that the tank was probably overstocked - mainly due to the fact that when we put the fish in, we underestimated how big some of them would grow. The tank always looked very "busy", but this morning, their corpses lined the entire bottom of the tank, with only one listless malawi cichlid and one listless catfish swimming around the corpses. This might sound daft, but I find this a wee bit upsetting. :( God help anyone who pisses me off this morning! :mad: