That video leads me to beleive that they are dogfish/bowfin they can use their swim bladder as lungs and frequently gulp air from the surface if they are low on O2.
The bowfin has a light covering of rounded, overlapping scales, a large mouth, and sharp teeth. Its swim bladder is capable of functioning as a lung, and the bowfin can survive out of water for a day. It prefers sluggish water and surfaces occasionally to gulp air.