Fish populations worldwide have been collapsing over the past few decades. In the 2nd half of the past century, ocean fisherman used more boats and better gear to quadruple the number of fish they caught. By 1989, fisherman worldwide were catching all the fish the ocean could produce and since then we’ve begun to overfish. What this means: fish populations in many parts of the world are crashing.

Scientists warn that if we continue on this trajectory we could deplete our oceans by the middle of this century. There are ways to avoid this without giving up eating fish altogether. We simply need to eat lower on the fish food chain. That means avoiding big fish like tuna and salmon or slow growing fish like Chilean seabass (lifespan of 40 years) and Pacific rockfish (one caught in 2001 was 205 years old) and opting for smaller fish like sardines and anchovies or vegetarian fish like catfish and tilapia.

If you’re confused about which fish are more sustainable, the Monterey Bay Aquarium puts out a green fish guide. Catfish is one fish that earned a “Best Choice” label. According to the guide, U.S. farm-raised catfish (avoid imports like basa and swai) is farmed in an ecologically responsible manner.

“Raised in closed, inland ponds using recirculated fresh water and fed a mostly vegetarian diet of soybeans, corn and rice, U.S. farmed catfish is considered to be one of the most sustainable fish species available. Closed, inland ponds dramatically reduce the risk of farmed fish escaping and spreading disease to native wild populations. Their primarily vegetarian diet, with extremely low levels of fishmeal, reduces the number of wild fish caught.”

My father who grew up fishing on the San Francisco Bay is a die-hard salmon fan, but eating this local fish has become unsustainable; since 1950, about 95% of California’s wild salmon population has disappeared. My dad is tring to branch out beyond his old favorite. In this video, he swaps salmon for catfish for a family dinner and discusses mercury levels in fish.