A small school of half-size fish in the deeper part of the lagoon where there will be more freshwater than in the shallows where the larger schools of juvenile fish predominate.
These are deeper-bodied than the smaller fish seen in the shallows.
(Edited to fix typo)
There are usually schools of juvenile mullet in the tidal shallows of the lagoon. I think they are grey (sea) mullet, mainly because of the amount of freshwater present, between tides.
Photos from above water with the DSLR. The fish all crowded around the GoPros and were too close to the lenses to get any photos in the shallows out in the sun. I did get some GoPro photos nearer the rocks - uploaded separately.
DSC00713
Steve's photo DSC00698 zoomed in
photo DSC00684
Found amongst among sand grains from a seawater rock pool sample
Amongst the sand grains in my sea water/rockpool sample.
Found in the sand grains with a rock pool/ sea water sample