Trout and Water Temperature

I’ve always been interested in Trout behavior and why two trips to the same location can sometimes give such different results.

So after recently fishing in one of Victoria’s western lakes which had a very cold water temp of around 8 degrees, I wanted to try and learn a bit more about how trout and temperature react with one another.
From the info and reading I have done here is a summary of what I found.

• Optimum water temperatures for Rainbow and Brown Trout are 10-22°C and 4-19°C respectively.

• Warmer water contains less oxygen than colder water. As temperature rises and dissolved oxygen decreases, fish begin to experience stress.

• Rainbow trout are said to be able to survive in temperatures up to and exceeding 25°C, but stop growing at 23°C.

• There is a considerable consensus that all three major trout species (brook, brown and rainbow) begin to experience some level of stress at around 20°C, with that stress increasing rapidly as the temperature rises further.

• It also seems to be common consensus that it may not be the actual temperature of the water that can make the difference to trout’s feeding behavior, but whether it is stable or changing. Apparently a changing temperature can be the catalyst to when they feed aggressively or not. Some people say that only when the temperature is trending upwards will it bring the fish on the bite, while others say it doesn’t matter as long as it is changing, up or down.

• For spawning and egg production, brown trout need 6-10° C and rainbow trout 9-14°C.

• Growth of both rainbow and brown trout is best at about 15°C.

I wasn’t really able to find any specific information on trout and cold water, but will keep on looking for more answers. We did manage to catch a few fish in the 8°C water, but I can’t help but think we may have done a lot better if the water was a bit warmer?

Now this info has been sourced from websites all over the globe, but mainly government agencies in Australia, so I still urge you to take it all in with a grain of salt and use it as more of a guide than fact.

We would be interested in hearing about your cold water trout theories and experiences.