Hi Mr. Jabara,
Mullet feed on diatoms, which is a major group of detritus and algae. Detritus is non-living particulate organic material, such as dead plants or decaying leaves. Mullet will feed on aquatic plants and mud. They will once in a while eat other tiny marine forms such as mollusks and very tiny crustaceans. They will also eat doughballs!
The exact reason they jump? Scientists are not really 100% sure. But here are some of the major theories:
1.) They jump to try and shake the sea lice or clinging parasites.
2.) They jump when frightened.
3.) They jump during their spawn to break open their egg sacks.
4.) They jump to let others in their school know where they are.
Cheers for the all-American mullet, and thank you for sending your question to The Online Fisherman.
Captain David M. Rieumont
The Online Fisherman Inc.