New research shows that fish poop can provide a better picture of stress levels

From the moment the fish is caught until the blood sample is taken, the level of stress hormones in the blood can have risen 1,000 percent. In the feces, however, the level of stress hormones is more stable, which can provide a more reliable and accurate picture of the underlying stress level of the fish.

When explaining adverse events in the aquaculture industry, stress is often cited as a triggering or contributing factor. Stress levels are traditionally documented through a blood test, but researchers believe that feces, or fish poo, can provide a more reliable and accurate picture of stress. The reason is the fish's rapid stress response: During the short time it takes to hog, anesthetize and take a blood sample from fish, stress levels can increase by several hundred percent.

– Then it is difficult to say for sure whether the stress was triggered by the unwanted event, or whether it was the blood sampling that stressed the fish, says Johan Rennemo, veterinarian and product manager for health monitoring at Skretting.

– In feces, we will find the stress levels as they were hours before the handling stress. It takes time for the increase in stress hormones to become measurable in feces, while the blood sample tends to reflect the stress that occurs in connection with the actual sampling, explains Rennemo.

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