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Fish Food Supplemented with Creatine May Enhance Swimming Endurance

Kyle Winders, an MU fisheries and wildlife major from Gower, Mo., monitors a rainbow trout as it swims within a special double-walled Plexiglas tube designed to measure the fish's endurance. Winders is an undergraduate student working with MU researchers Rob Hayward and Eric Berg, who are studying the effects of creatine on fish growth and endurance.
Photo by Steve Morse

Creatine Fish (WMV)

By Jason Jenkins

Creatine, the performance-enhancing supplement made famous by Mark McGwire when he broke Roger Maris' single-season homerun record in 1998, may also enhance the growth and endurance of some fish species, University of Missouri researchers said.

In a recently completed preliminary study, MU fisheries professor Rob Hayward and MU meat scientist Eric Berg found that some rainbow trout, when fed a diet supplemented with 5 percent creatine, showed a dramatic increase in the length of time they were able to swim against a controlled current.

"While this study is by no means definitive, there is some indication that swimming stamina was enhanced," Hayward said. "The difference was striking, as some fish fed creatine swam 8 to 10 times longer than those in the control. If this were a random phenomenon, you'd expect to see something in the control group, but no single fish in the control showed the same stamina."

Should the dietary supplement prove effective, it could have implications for both owners of lease-fishing operations and for open ocean aquaculture, he said.

"Sportsmen would likely pay a premium for a fishing experience where the fish struck the bait harder and fought longer," Hayward said. "And as the aquaculture industry continues its move into the open ocean, creatine might provide a means of improving growth rates and survivorship in stronger ocean currents."

To test the trout's swimming stamina, the researchers used a unique apparatus: a double-walled, Plexiglas swim tube.

"In essence, it's a water treadmill," Hayward explained. "The fish is placed in the inner tube, through which a regulated current is sent. When water reaches the end of the inner tube, it re-circulates back to the front of the outer tube. This study would be impossible to do without it; there's no better way to quantitatively measure endurance."

MU undergraduate researchers Amber Wiewel, a junior fisheries and wildlife major from Maywood, Mo.; and Kyle Winders, a sophomore fisheries and wildlife major from Gower, Mo., assisted Hayward and Berg with the project.

In addition to trout, the researchers tested creatine's effects on bluegill, but they didn't see any significant differences. "Bluegill are relatively sedentary and are reluctant to swim, so differences weren't pronounced," Hayward said.

According to Berg, that finding is consistent with the properties of creatine, which he has studied in pigs and chickens since the late 1990s.

"Creatine doesn't make you stronger or bigger by itself, but it helps the system work better to get stronger or bigger," he said. "It's one of the first energy reserves for muscle contraction and essentially enhances the actions of exercise."

Hayward added that each trout's genetic makeup could affect individual responses to creatine. "I've seen that (variation) from people in the gym. Not everyone responds the same."

In research with pigs, Berg found that creatine — which is a naturally occurring amino acid, not a hormone or steroid – improved pork quality by making juicier meat. In fish, the goal would be to increase muscle growth.

Although the MU researchers have an exemption, creatine currently is not approved by U.S. Food and Drug Administration for fish consumption. That might change if the diet proves effective and economically feasible, Hayward said.

"Our next step is to conduct tissue analysis, and if we find favorable results, we might pursue another study," he said.