I was in Daytona, Florida, in shallow warm water, when a very large fish swam close to me. It was about 6 ft long and dark coloured, even black.

At first I thought it was a shark, but I didn't notice a large dorsal fin. Another swimmer said it was a dolphin but it was too dark for that.

Is there such a thing as a massive catfish that likes warm Floridian water?