Do anaesthetics trigger stress?

New research could improve the welfare standards of millions of fish used by scientists around the world. The study, published in PLOS ONE, is one of the first to formally assess the welfare implications of anaesthetics on fish. Researchers use fish to study the developmental origins of health and disease. The work, carried out in collaboration between the University of Bristol's School of Veterinary Sciences and AstraZeneca Brixham Environmental Laboratory , investigated whether scientists are using the right anaesthetics and if current best practice for fish could be improved. The research team's behavioural study evaluated nine of the most commonly used anaesthetics and performed preference tests using adult mixed sex zebrafish ( Danio rerio ), the most commonly held laboratory fish, to record their responses. Video tracking software measured swimming behaviour related to dislike for each anaesthetic at 50 per cent of its standard recommended dose compared with clean water in a flow-through chemotaxic choice chamber. The aim of the research was to find out if anaesthetic compounds cause changes in the swimming behaviour of the zebrafish and whether the potential stress induced in these animals is inhumane.