Aquaculture, or 'fish farming' is an innovation of recent decades to meet growing seafood consumer demand & overfishing in the oceans.
As of right now, Shellfish is the most sustainable form of aquaculture that exists. Oysters and clams filter the ocean as they grow. Other more commonly eaten fish like salmon and tilapia are also making their way to becoming sustainably farmed.
Watch this TED Talk by Perry Raso to learn about the importance of sustainable aquaculture.
If you're ever in Rhode Island, go for a meal at his restaurant - Matunuck Oyster Bar!