I have had my 40 gallon planted tank set up since before Christmas; we added fish about six weeks ago (3 Danio, 3 Platy, 2 Catfish, and a Gourami) and with the exception of the Danio (we lost all three of them over the course of the weeks) the fish were happy and thriving. Until today, when I came home and found 2 Platy and a Catfish missing. After thoroughly searching the inside and around the outside of the tank and finding no corpses, we have concluded that the fish probably fell victim to one of our housecats. We have three, and up to now, they have only made one or two half-hearted attempts to get at the tank; there is a lid on that is always closed, but it has the standard cut-out space for the heater and filter, and it is definitely large enough for the murderers-ahem!-my beloved felines to reach in and grab a snack. What I want to know is if there is anything available or anything that anyone has DIY'ed that might prevent this happening to me again. I was thinking about trimming a piece of screen material to go under the lid, but it would still have to have a cut-out for the heater and filter.