While not an adequately scary picture, that's one HUGE catfish. For perspective, those little white things around it are oyster crackers. Yeah. Now you're scared. There's also gnarly bumps on its head, not unlike a shark. Maybe more like a manatee, but they aren't scary.
Why are there oyster crackers in my pond? After all, they aren't made of oysters. In addition to the oldest, biggest catfish in the world, there are three very large grass carp. Since it's been such a dry summer and they've eaten every last pond weed, they've started on my water lillies. Now that's a problem. SO I've fed them crackers and thrown random weeds in the pond for them to eat.
Perhaps the greater question is why would I want to swim in a pond with soggy crackers, dead weeds AND huge fish.