UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
How much percentage of oxygen does a fish need?
Question Date: 2015-04-14
Answer 1:

That's an important question! About 21% of the air we breathe is composed of oxygen. Even though fish live in water, they need oxygen too. Unlike us, fish do not have lungs, but instead uptake dissolved oxygen from the water using their gills. The concentration of dissolved oxygen in water is much lower than the amount of oxygen in the air.

Fish do best in water that has dissolved oxygen which is at least five parts per million (=0.005 grams of oxygen in 1 liter of water). If the dissolved oxygen drops below about 2 parts per million, most fish will suffocate and die. Therefore, it is important that lakes, rivers, and streams remain relatively oxygen-rich. Things that can affect dissolved oxygen concentration include: temperature (colder water will hold greater oxygen concentrations) and pollution (things like sewage in water can cause blooms of bacteria that use up the dissolved oxygen, hurting fish).

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use