Changing the environment of a fish causes stress that robs fish of essential nutrients and can weaken their immune system. First Defence is scientifically designed to provide stress relief and support the immune system, helping fish cope with stress due to bagging and shipping from the store to your tank, water changes, new fish additions, disease treatments, and other environmental changes.

First Defence can be added to the fish bag when acclimating new fish or as fish/coral dip.