This picture has been popping up a lot lately, sometimes the location is Alabama, sometimes it's Tennessee (and probably some other places that I have missed), but the message is typically the same: Can you believe what's in the lake! I'm never going swimming again!
Here's the thing: this is a Northern Watersnake (Nerodia sipedon), a very common species on the East Coast of the United States, and the snake is eating a catfish (looks to me like some sort of Channel Catfish). Watersnakes tend to eat things that live in the water, like fish and frogs. So, this is basically a picture of a common snake eating something that they normally eat. This kind of thing happens around us all the time and especially when we're hanging out around the water. We are just not often lucky enough to see it!
If a watersnake eating a fish is enough to keep you out of the water, then I am sorry to tell you that you are going to have to stick to swimming pools from now on. But, I hope you will realize that a picture of a snake eating a fish is not something to be afraid of and is no more terrifying than a picture of me eating lunch (perhaps less so).
I think I can trace this viral photo to a couple of Twitter accounts: @TerrorStory and @Unsolved_Scenes. Both of these handles just tweet pictures with dubious explanations but without much in the way of context (or photographer credit). If you check them out, you can see that these accounts have hundreds of thousands of followers between them. The picture of the Northern Watersnake has now been retweeted over 10,000 times with the title, "Why you shouldn't swim in rivers" I suggest an alternative headline, "Why Twitter shouldn't make you scared of native and harmless wildlife".