Between yesterday and today I noticed that 2 of my small fishes have disappeared. No remains at all have been left and I can't find anything on the carpet. Unless my pictus cats are swallowing these fishes whole, I have no idea where they have gone. I have an oto that's about 1.5 inches and a zebra danio that's about 2 inches that has disappeared. The pictus cats, the largest is about 4 inches and the other 2 are about 2.5 inches. They are very well fed, so I don't think the pictus went out hunting when the lights when off. The water parameters are good, no amonia, no nitrites and only traces of nitrate. The tank is 55 gallons and the residents are 3 pictus, 7 tiger barbs, 1 pl*co, 2 (well 1 now) oto, and 7 (now 6) zebra danios.