These start-ups are growing fish in a lab to help save the world's oceans from overfishing

A couple years ago, there were no companies focused on lab-grown seafood. Now a handful have cropped up, including Finless Foods, Blue Nalu, Wild Type and Seafuture. And their founders hope fish grown in a lab can help them break into the more than $120 billion seafood market, and make it more sustainable in the process.