Cannabidiol (CBD) could reduce stress experienced by fish being shipped for sale as part of the ornamental fish trade, new research shows.

Adding CBD to the transportation water of ornamental fish can help improve the welfare of fish after shipment, a study led in partnership by the University of the West of Scotland (UWS) and Mars Petcare’s leading science centre, Waltham Petcare Science Institute, has found.

In an experiment using variatus platys, a popular breed of aquarium fish, researchers found that fish which had been transported in water infused with CBD showed a drop in stress-related behaviours, such as biting, chasing and swimming erratically.

The ornamental fish trade is a multi-billion-pound industry which involves more than 125 countries across the globe, transporting more than one billion fish annually. It involves the sale of fish for uses such as in home aquariums and in decorative tanks or ponds, often in locations far from their place of origin.

However, stress caused during transport can the weaken immune response in fish and increase their risk of disease, while anxiety-induced behaviours can result in physical harm, both of which require fish to be quarantined and treated before they can be sold. 

The study found that water containing CBD - a natural compound known for reducing anxiety, inflammation and pain - produces a calming effect by potentially modulating neural pathways related to fear, with no detrimental impact seen to the protective layer of mucus which covers fish skin.

Researchers say the findings highlight the potential for CBD to be used within commercial water conditioners to reduce the effects of transport stress within the trade, presenting a welcome welfare boost to the industry.

Leading on UWS’s involvement in ornamental fish welfare is Professor Katherine Sloman, who said: “Improving the welfare of fish transported internationally is of importance both ethically and economically. Within the ornamental fish trade, we know that transport-induced stress can lead to erratic or aggressive behaviour, which can exacerbate levels of anxiety and potentially lead to physical damage.

“Our research shows that a relatively small change to the way ornamental fish are transported, such as adding CBD within commercial water conditioners, could transform the industry and help safeguard the wellbeing of countless fish.”

A relatively small change to the way ornamental fish are transported, such as adding CBD within commercial water conditioners, could transform the industry and help safeguard the wellbeing of countless fish.

Professor Katherine Sloman

Dr Donna Snellgrove, Fish Research Manager at the Waltham Petcare Science Institute, said: “Improving the welfare of fish during transport by minimising stress is important to ensure the health of fish within the trade. We are proud to be able to establish scientifically supported solutions that will make a difference to such a large number of fish.”

We are proud to be able to establish scientifically supported solutions that will make a difference to such a large number of fish.

Dr Donna Snellgrove

The research directly addresses the United Nations Sustainable Development Goals, particularly Goal14, Life Below Water, and Goal 17, Partnership for the Goals.