A GoPro.  They strapped a GoPro to a redfish.

I think. Check out the 2:20 mark to know for sure.

Aftco is producing some great content these days . . . this has some fantastic drone footage of South Florida fishing, and also a GoPro strapped to a redfish.

Travis Thompson
About the Author

A 5th generation, Floridian, Travis has been hunting and fishing his home turf for as long as he can remember. When he's not in the woods or on the water, he's spending time with his kids, Olivia and Will, the lovely Mrs. Thompson, or futilely attempting to train two French Brittany Spaniels . . .