The Stream Doctor

December 13th, 2004

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.

Q. What is the pH level in water needed for rainbow trout to survive? Can rainbow trout survive in an acidic environment?

A. Although you are asking specifically about rainbow trout, it will be easier if I respond for trout, in general, and add any specific information about rainbows.

Trout generally prefer pH levels between 6 and 9, with 7, of course, being neutral and acidic conditions below 7 and basic conditions above 7. Thus, obviously, they prefer pH conditions around neutral but slightly more on the basic side.

As for survival under acidic conditions, it depends on the species and the softness of the water; trout are more sensitive to acidic conditions in soft water than they are in hard waters containing higher concentrations of calcium and magnesium carbonates. Anyway, direct toxic effects on adult salmonids has been observed at pH levels between 5.5 and 4.5, and rainbow trout appear to be more sensitive than other species to acid stress. Brook trout are more tolerant than other trouts.

If you have a question, please feel free to contact me.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at

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