A Tokyo aquarium has a unique catch.
Tokyo Sea Life Park is the only aquarium to have the ocellated ice fish (Chionodraco rastrospinosus) -- a unique vertebrate that has gin-clear blood and no scales, Agence France-Presse reports.
The species lives 3,280 feet below surface in the icy waters off Antarctica. The species doesn’t have hemoglobin, the protein that makes blood red and carries oxygen.
"Why is it the fish lost haemoglobin? More studies are needed on the question," Satoshi Tada, an education specialist at the center, told the news outlet about the mystery surrounding the fish’s transparent blood.
The fish were captured by Japanese krill fisherman in 2011, the Independent reports. Tada says a male and female have spawned, giving scientists more specimens to study and the chance to discover how the ocellated ice fish can move oxygen around its body without hemoglobin.
Tada points to this ice fish’s large heart as a potential factor, he told AFP.
The creature's journey, from its capture to Tokyo, was also a feat.
“It must have been really hard to bring one back alive as you have to keep them constantly at a temperature close to zero degrees,” Tada says about the fish’s journey.
Apparently, the ice fish is a tasty meal.
“I’ve never tried it myself, but according to fishermen who have eaten it on the boat several times, it tastes really good,” Tada says.