I have an aquarium with 3 iridescent shark fish, 2 swordtails, 3 tetras, and 3 small red fish which I cannot recall their exact names. The problem is that one of the smaller red fish has gone missing. I can't figure out what could have happened. I checked the filter, I looked under all the aquarium decorations, I even checked the entire room in the case that it might have jumped out, but I doubt that happened. My only other conclusion is that he was eaten. CAn any fish experts shed some light on this mystery? Thanks.