The almost infinite variety of life on Earth keeps surprising and puzzling us. For example, the ocellated icefish (aka Chionodraco rastrospinosus) that lives around 3,000 feet down in the cold dark water surrounding Antarctica might look like an ordinary fish at first glance, but it lacks two things that most other fish have: hemoglobin and scales.
The lack of hemoglobin means that its blood is clear like water, setting it apart from pretty much all other living creatures that have bones (because bone marrow produces red blood cells).
The Tokyo Sea Life Park is the only aquarium in the world that has ocellated icefish in captivity, and their pair has spawned a few months ago. The video below was taken there:
Scientists hope the mated pair of icefish and their offspring in Tokyo will help researchers unlock the secrets of how the fish manages to survive without hemoglobin to carry oxygen to its cells.
It's possible, some scientists speculate, that the icefish's unusually large heart might help move oxygen through its body using blood plasma instead of hemoglobin.
Also, with no scales to get in the way, the icefish may absorb some oxygen directly through its skin: Cold, polar water is richer in oxygen than warmer waters.(source)