Well that's the first salt water aquaponics system I've ever seen!
So in the desert, you will need to keep the water cool, and the direct sun off. Using wide eaves to keep the sun off during the hot part of the day, but delivering direct light in the winter, and the dawn / dusk would be useful.
Also having a double roof where air is free to flow between and move the heat out (like a double roof) reduces the internal heat a lot:
A reflective ceiling would also distribute ambient light more efficiently throughout the environment as it comes through the windows and reflects off the floor. Or use a translucent inner roof.
Also increasing the size of the pool, and have a decent portion of it underground, even under the floor. The fish like darker water anyway. If you're using deep grow beds like in the pictures, then have them deeper than normal so there is more thermal mass, and thermally couple it to the ground.
Just some thoughts...