People often ask us how we get such good photos of fish, particularly how we coax them to stay still for the camera. Although we’d like to be able to say that our calming, zen-like influence renders them still, in reality some of our close-up pictures are taken while the fish are under anesthesia. It’s common practice in fisheries biology to anesthetize fish lightly in a solution of MS-222 and Stress Coat, which temporarily immobilizes them and reduces their wiggling during the data collection process. In addition to being easier to handle and measure, this protects them from scale loss, minimizes the processing time, and overall reduces the stress of handling and captivity. Once fish are measured and weighed they are placed in a bucket of fresh water, where they recover within a minute or two and are released back into the river.
Photo source: FISHBIO