Long Island, Bahamas, at sunset:

A group of Nassau groupers (Epinephilus striatus) from a spawning aggregation at 25 meters depth, rush together to release gametes.

At the moment of gamete release, a white cloud of eggs and sperm is expelled. The fish twist away from the cloud at high speed.
A couple of seconds later, a single pair arch above the cloud, leaving a separate trail of eggs and sperm.

Finally, the gametes start to disperse with the eggs almost immediately fertilized.

 

Photos by L. J. Bell Colin