Even a small bump in resilience could have huge consequences for fish farming. As things stand, around 40% of fish farmed worldwide die before they can be harvested. Imagine being able to prevent even part of that loss.

This isn’t the first time scientists have tried to tweak the genomes of farm animals. Of course, farmers have used selective breeding to try to make animals big, muscular, docile, and easy to rear for generations. But gene-editing tools like CRISPR should allow them to fast-forward the process.

CRISPR offers a major advance over previous gene-editing tools. For a start, it’s relatively cheap, quick, and easy to use. Newer forms of CRISPR allow scientists to do more to a genome, too. Some forms allow us to change the base letters of DNA, such as swapping a C for a T. Others let us insert entirely new genes.

So perhaps it’s no surprise that scientists have started experimenting with CRISPR in farm animals. One popular target is a gene called myostatin, which codes for a protein that controls muscle growth. Interfering with this gene can lead to muscle overgrowth. In other words, you end up with big, muscly animals. And, eventually, more meat.

Scientists have already experimented with using CRISPR to generate super-muscly cattle, pigs, sheep, rabbits, and goats. These studies have not had perfect results. Many of the animals didn’t survive infancy. And a lot of them had weirdly large tongues.

Research in fish is also well underway. Using CRISPR to target the myostatin gene, scientists in Japan have generated red sea bream that are bigger and heavier, with 17% more muscle than their unmodified counterparts, despite being fed the same amount of food.