Moved from Dark Fishflies.

The fishfly appears to be Nigronia fasciatus, and a male, I think. A Guide To The Megaloptera And Aquatic Neuroptera Of Florida (1) keys:

Wings with large white areas more or less continuous, especially across the middle; anal area of hindwing white; male antennae modified pectinate; female antennae serrate--->Nigronia fasciatus

Wings with white spots isolated often associated with crossveins; anal area of hindwing brown; male and female antennae serrate--->Nigronia serricornis

Your specimen seems to have the large white area on the forewing and those antennae appear to be somewhat comb-like, esp. compared to the other images in the guide, of what appears to be N. serricornis. One hindwing is visible, and I think I see white on the anal area (corner close to the body).

Patrick Coin
Durham, North Carolina