LOL Mutation is a part of life. But I haven't encounter species of mutated tilapia yet. Many of the tilapia at the Red Hill were taken, ranging from 6" to 18", and did a genetic test for mutation. They only found hybridization from both genetic and visual. I wouldn't doubt there's somekind of mutation from the older species, but it takes at least 100 generations to have such mutation. So far, the younger generations haven't got any trace of mutation yet.
Don't be so wearied about hearsay from those who don't have the scientific background. If you worry about the Sea so much, you should also be wearied about the water you're drinking as well. The ground water contamination that you're using, as well as the water from the Colorado River being imported, is much much higher in heavy metals that it will kill you faster than the the fish at the Sea. However, you're right about the Sea's tilapia, that the fish will kill you much sooner than the mutants, since the tilapia's meat is high in omega 6, which leads to plenty of side effects if consumed daily in large quantity (6oz of filet/day for the next 3 years)