Kids Web Japan

A Very Special Kind of Water

What happens to fish in this water?

Both freshwater and saltwater fish have body fluid with a salinity (salt concentration) of about 1%. Because this special water has a salinity close to that of their own bodies, the fish have less trouble regulating osmotic pressure than they would in seawater, which has a salinity of about 3.5%. Scientists have learned that this property of the water improves the fishes' metabolisms.

Fish control the concentration of salt in their bodies by a process called osmoregulation. Having too much salt in their body fluids would cause the fishes' cells to absorb water; having too little salt would cause the cells to lose water. Both of these conditions would be harmful to the fish.

This is special water containing only a few of the substances that make up seawater. The water was developed in an experiment aimed at making water that is habitable for both freshwater and saltwater fish and contains as few substances as possible.

This special water is called "Magic Water". It was developed by Yamamoto Toshimasa, a teacher at the Okayama University of Science Specialized Training College.

Yamamoto hopes that the water will be used to breed marine fish in land-based water tanks. This would protect the fish from such dangers as marine pollution while opening up a new source of safe, inexpensive seafood.