The sea turtles' fish habit has been described as "potentially fatal"
Two turtles at Birmingham Sea Life Centre with an unhealthy taste for fish have been retrained by a schoolgirl to eat their natural vegetarian diet.
The pair, Gulliver, 55 and Molokai, 33, live in the centre's ocean tank and used to steal fish left for the sharks.
Work experience pupil Laura Deeley, 17, from Halesowen, used a clicking device to help retrain the green turtles.
She taught them to associate the clicks with broccoli and potentially saved their lives, staff said.
Emma Dowler, the centre's senior aquarist, said she was impressed with the teenager's efforts.
"Laura has worked a minor miracle. We were worried that Gulliver and Molokai had developed such a liking for fish that we'd never get them back on a proper diet."
Alex Gerard, the Sea Life Centre's turtle specialist, said a fish-only diet was very dangerous for the pair in the long term and would have been "potentially fatal".
He said green turtles typically ate sea grasses and were not designed to digest fish as adults.
"They would pile on the weight and probably store fatty deposits around their major organs, which could lead to a heart attack and obesity and shorten their life."
The centre believes Gulliver and Molokai are the largest examples of giant sea turtles in Britain.
Staff explained that the sharks are afraid of the pair, which enabled Gulliver and Molokai to steal their dead fish.
Laura, who is studying biology and maths at Old Swinford Hospital in Stourbridge, was given a Nuffield Science Foundation bursary from create a future to train the turtles to make it easier for staff to give them health checks.
She said: "When I learned about the eating problem I realised I could probably tackle that at the same time, but it worked far better than I'd hoped."
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