Two common ways of handling live fish are by netting and by using a scoop. As the term suggests, netting involves catching the target fish in a fishnet and lifting it out of water and into contact with air. Usage of a scoop is similar to using a net, but the fish stays immersed in water.

Sticklebacks and bishops have been shown to have significantly higher increases in breathing rate when handled with a net compared to when being handled with scoop. Cortisol levels were similar for both net and scoop, compared to control fish, which had significantly lower cortisol levels.

Courtesy Yoko Dam

As can be expected, any kind of handling will increase the stress of fish. This can include increased respiratory rate and increased cortisol levels. As such, it would be best to handle fish with a scoop or keep them submerged in water to reduce stress. Lower stress means higher life expectancy and better growth. Therefore, it would be in both the fish and the owner or farmer’s interests to keep stress as low as possible. However, responses to handling may differ between species, so more study will be needed.