In a school of sardines. Don't hold back!

Divers in a large school of sardines.

Shot in Panglao, Bohol, the Philippines.

Olympus e-pl5 in PT-EP10 housing, Olympus 9-18mm, AOI 4" dome port, two sea&sea YS-D1 strobes.

The strobes were fired because I wanted some shine on the school of fish, but I'm not sure it got me anything other than some extra backscatter at the range and power I was at

I followed the 700px long side rule, but I feel it's a tad tiny. Full version available here if anyone is interested:

https://500px.com/photo/182950633

Please critique anything and everything, and don't hold back! I really value any negative feedback you have, constructive or not.

First off I realize this is an older post but the critique still may help someone else who looks at this. The main thing I see is the composition should be adjusted to remove the white space in the upper left. It's very distracting and nothing is there which serves no purpose. I did some messing around and if this was cropped and rotated clockwise slightly to remove the white in upper left and waisted space of all blue in the lower right, it would draw the viewer in more and make the school of sardines seem more grand. There's just to much waisted space in this image but it's possible to make an adjustment and make this image pop substantially more.