• Question: Why can sea fish only live in salty water?

    Asked by chrisb on 23 Apr 2020.
    • Photo: Katherine Benson

      Katherine Benson answered on 23 Apr 2020:

      These fish have become highly adapted to living in the saltwater of the sea, which is their natural habitat. Their blood and cells have a really high salt concentration, if they’re put into freshwater, their blood and cells will begin to fill with water, they will get all bloated up, and die.

Comments

  • Photo: Amy Heather

    Amy Heather commented on :

    So just like humans, fish also have this function/job called ‘osmoregulation’. Osmoregulation is the control of how much salt is your body, so for humans we drink water to balance our the water and salt ratio. For some fish like tuna, they live in salty water all year round. Tuna will get rid of the extra salt using their kidneys and gills. Other fish like salmon and trout, live part of the year in ocean and part of the year in rivers. These fish are super smart and can figure out that when they move to the river water, they need to change how much salt they get rid of using their kidneys and gills. Hope that helps 😀