The trout are bizarrely muscular, with rippling abdomens that resemble six-pack abs and dorsal humps that give the impression of bulked-up shoulders. But these bodybuilder fish didn’t just develop that way on their own; a University of Rhode Island scientist spent 10 years genetically engineering them for increased muscle mass, according to Science Daily.

It’s all part of a goal to grow larger trout in commercial fisheries without increasing the amount of food they’re given, and professor Terry Bradley believes he’s finally obtained results that could be a huge boost to the aquaculture industry.

Bradley and his research team found a way to inhibit myostatin, a protein that slows muscle growth, to increase the number of muscle fibers in the bodies of rainbow trout.

After injecting 20,000 rainbow trout eggs with DNA designed to inhibit the protein, the team found that 300 of the hatched eggs carried the gene that increases muscle mass. Those fish were spawned, and subsequent offspring have also carried the gene.

"The results have significant implications for commercial aquaculture and provide completely novel information on the mechanisms of fish growth,” Bradley told Science Daily. "The results also allow for comparisons between the mechanisms of growth of muscle in mammals versus fish, and it could shed light on muscle wasting diseases in humans."

But the same muscle mass that could increase yield at fisheries could also help the fish break out and wreak havoc on the environment. U.S. fisheries already have significant problems with escapes, hence the current problems with invasive Asian carp in the Mississippi River Basin and beyond.

Researchers who have studied the effects of escaped transgenic fish recommend breeding them in closed systems on land to prevent such occurances, especially because genetically engineered fish are often able to overtake native species.