Okay, we made up the last bit, but these fish have been altered to grow far more muscular than normal trout:
The bodybuilder stature of the trout comes from turning off myostatin, a protein that normally slows muscle growth. Researchers had known of a natural myostatin mutation that allowed for 20 to 25 percent more muscle growth in Belgian blue cattle, but did not know if the same would apply to the different mechanism of muscle growth in fish.
Terry Bradley, a fisheries and aquaculture expert at the University of Rhode Island, worked with a group of grad students for 500 hours to inject 20,000 rainbow trout eggs with different DNA snippets designed to block myostatin.
Photos at the link.