Beautiful colors and a very nice photo. I can't see that anything should be different. You might want to play around with the cropping a little and see how you like the groupings. For example, The group is split right in the middle of the picture: the fish are in the top half and the lillies in the bottom. Try cropping so that maybe the lillies are in the lower 2/3 and a couple of fish in the upper third. That to me would seem a more pleasing composition. Or the other way, the fish in the upper 2/3 and a few plants in the lower third. There's almost too much in the photo, even though your subjects are beautiful.
Just my thoughts.