Indoor fish farming seems like a much more practical approach to solve the problems inherent in catching wild fish to eat (and the pollution that outdoor fish farms cause), and a much more logical next step for seafood than lab-grown muscle tissue.

Lab-meat makes most sense for beef, which is an incredibly inefficient and habitat-destroying food source, and is also often served in a processed form anyway, ie as minced-beef in burgers, bolognese, sausages, etc, etc.