First, it’s important to know that fish are covered in a thin layer of mucus. This slimy coating (it is also called a “slime coat”) is known to keep fish healthy by warding off pathogens. Scientists ...

Mucus is a miraculous substance. It’s in our noses, of course—but it also helps us swallow. And it lubricates our eyes, so we can blink. But it’s not just us. Mucus is ubiquitous in the oceans, too.

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