Common diseases in marine ornamental fishes

Welfare and health of marine ornamental fish can be influenced by several environmental, nutritional and biological factors. Considering that the description “marine ornamental fish” includes over 1500 species of dozens of families with extremely different biological, nutritional and environmental requirements, it is obvious that extremely different health problems may be encountered by these animals during all the phases of their life, from capture or artificial reproduction to confinement into public or private aquaria. Keeping fish in a confined/artificial environment, whether in a farm tank or a private or public aquarium, generally results in their forced coexistence with stressful conditions that may adversely affect their wellbeing, making them prone to several diseases, primarily those due to parasitic and infectious agents. The factors which most commonly favor the development of a transmissible disease in a fish population held in a confined environment are numerous, such as water quality, nutrition deficiencies and/or imbalances, overcrowding, inadequate sanitization procedures and, of particular importance, the introduction of parasitized/infected fish into the tank without appropriate quarantine and health checks. This chapter focuses on the most common and important diseases caused by infectious and parasitic agents in marine ornamental fish kept in aquarium systems.