Calling Gil, you gotta help

As I said previously, if any more fish died in the tank I would be sending for the CSI boys to come down and investigate for possible skulduggery.
Well, it seems that the warning was heeded.
Not because there have been no further deaths. Oh no!!
Because there has been. I came home yesterday to find that there was another fish missing, not dead, but missing. How convenient was that eh? Not only has my housemate appeased his appetite for wanton murder but he's also stashed the evidence. He denies it of course but its all a little bit too coincidental. Unless of course it's the fish that are out to frame him by doing in one of their own and then hiding, or maybe even eating, the body.
I may have to rig up a secret webcam!