Photo/Illutration Although the eastern flower porgy on the left, pulled from a depth of 170 meters, has bulging eyes due to the sudden change in water pressure, the fish regains its health once placed in Kotaro Yoshimura’s “aquatic life containment equipment.” (Provided by Aquamarine Fukushima)

IWAKI, Fukushima Prefecture—An aquarium worker here has created an affordable, compact pressurized container that can restore the health of deep-sea fish that look like they have “exploded” at the surface.

Kotaro Yoshimura, 47, an employee of the environmental conservation department at the Aquamarine Fukushima aquarium in Iwaki, calls his creation “aquatic life containment equipment.” It was patented in May.

Yoshimura has relied on special equipment for several years to transport deep-sea fish and other creatures safely to Aquamarine.

The eyes and internal organs of such specimens often pop out due to the sudden change in water pressure when they are abruptly brought to the surface. They frequently die during transfer.

Yoshimura knew that applying a sufficient level of water pressure to fish immediately after capture can restore their popped-out eyes and displaced internal organs.

A special container was already available on the market to pressurize seawater and reproduce an environment similar to that of the deep sea.

But the container was huge and bulky, and its design to use gas and other materials made it extremely expensive and difficult to handle.

Yoshimura asked a water tank manufacturer to help him test a more practical vessel.

He attached a hand-operated air pump to the lid of a cylindrical container that could increase the pressure of seawater poured into the vessel.

It is fitted with not only a pressure gauge but also a valve to release pressure and open the lid safely.

Yoshimura was inspired by these features 10 or so years ago when he saw the functions of a hand pump for gardening.

Water pressure at a depth of 100 meters is 11 times greater than pressure on land. Scuba divers must slowly ascend and decompress even from a few dozen meters below the surface to prevent a potentially fatal condition known as decompression sickness, or “the bends,” in which nitrogen in the blood forms dangerous bubbles.

Yoshimura himself dives deep in the ocean to catch fish for display.

“My system boasts such a simple structure that I once wondered why I had not devised the mechanism before, given that I had experienced decompression sickness,” he said,

The mechanism adopted for the vessel is expected to help deep-sea fish species return to their original state of health for sale, display and studies at aquariums, research institutes and markets.

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