At first, Carol Benge and her three-inch seahorse Louie had a pretty good life together. He bobbed around Benge’s fish tank while she fed him tiny brine shrimp. Then Louie got the bends—at least, he got the seahorse version of the bends.

In September, Louie wasn’t acting like his usual peppy self. He seemed to have trouble swimming. Small, pearl-like bubbles clustered on his tail—the telltale sign that led Benge to guess the sinister underlying cause was gas bubble disease.

Gas bubble disease happens when gases in a fish’s water get into its body.

It’s similar to the way the bends affect humans. When people stand on dry land, the air around them has pressure—just the right amount for a person to live in. But since water is heavier than air, divers going deep breathe extra-pressurized air from tanks. Even the blood and tissues in their bodies are under more pressure than usual. If a diver comes to the surface quickly, the pressure releases fast, kind of like bubbles in a can of soda. Those bubbles don’t belong in the human body. They can harm tissue or stop blood vessels from performing their imperative functions. Sometimes the bends make someone a little sore, and sometimes they paralyze or even kill.

The stakes were high for Louie too. “I wanted to save my little friend,” says Benge. She stowed Louie in a temporary tank and drove him an hour to the University of Florida College of Veterinary Medicine, where curious experts were eager to do an experiment. They wanted to put Louie in a hyperbaric chamber—precisely the treatment given to human divers suffering from the bends. In a hyperbaric chamber, a person breathes in pure oxygen at high pressure. This oxygen enters into the blood and can fix injured tissue.

Veterinarian-in-training Tatiana Weisbrod gently moved Louie into a Pyrex glass container along with water and a plant from his home tank. In the chamber, pressure applied over time shrank the gas bubbles in Louie’s body. Then the veterinarians released the pressure in the tank little by little. Just one treatment cured Louie.

God “made heaven and Earth, the sea, and all that is in them.” He “keeps faith forever.” (Psalm 146:6) Diving marine animals almost never get the bends. God made these creatures with particular abilities to store and redistribute oxygen through their bodies deep underwater. But gas bubble disease is common in aquariums, often affecting seahorses. Now—thanks to Louie—people know how to treat the problem in seahorses and other fish.