Lutjanus bohar Spawning Aggregation

In my ongoing pursuit of fish spawning aggregations, I spent several days with twinspot snappers (Lutjanus bohar) while I was in Palau recently. Here is one of my favourite images, taken in the low, moody light of 06:30:

Lutjanus bohar spawning aggregation in Palau
Lutjanus bohar spawning aggregation in Palau (License image)

Depicted is part of a gathering of thousands of fish, assembled for procreation en masse.

If you're a scuba diver and have dived in tropical waters, you've likely seen this species. Usually, the fish appear red, so people often refer to them as red snappers.

What became apparent several years ago when I first started trying to document these aggregations is that they can take on a rainbow of hues, as is apparent in this photo. I'm sure there's a reason they become one colour or another (or a mix of colours), but I haven't been able to figure out any pattern yet.

A big thanks to Frank and Ai Lin for accompanying me for these early(!) morning dives; and to Paul and Richard for taking care of me.

PS: Richard Barnden wants me to let you know that he taught me everything I know. Pfft. Not really of course, but his fragile ego requires constant reassurance, however ludicrous ;)