Atmospheric oxygen amount is around 21 mg/l and when we talk about dissolved oxygen in water it is around 15mg/l at 0 degree Celcius and 6-8 mg /l at 25 degree Celcius. My question is how fish live with this limited amount of oxygen?
Hi.
1. Fish gills are usually more efficient than lungs.
2. The ratio of gill surface area to body weight is much higher in fish than in humans (lungs surface area to body weight).
3. Fish has a lower metabolism due to being "Poikilotherm".
I just want to add some information. I think we do have different standards between animals living on the land and aquatic animals in terms of oxygen demand. A typical fish need dissolved oxygen (DO) of more than 5 mg/L. Even fish with labyrinths and lungs can breathe more efficiently. Catfish can cope in water with DO 2 mg/L. Because they can get oxygen via air-breathing.
Fish needs 4-6 ppm of dissolved oxygen in water and probably, fish do not spend energy in maintaining their position in water column and require minimum energy to maintain physiological activities, they survive in low dissolved oxygen level.
Thank you @Sina Javanmardi, Harish Muhammad, Madhav Bhilave Sir for sharing your knowledge.
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