Although there is a great deal of information on changes in gill structure as a result of infectious and non-infectious challenges, it is difficult to find a definition of gill health in the literature. Interactions between gills, fish, and a range of possible environmental changes have currently unknown effects on marine health and aquaculture production. Pisces may be able to reinforce certain changes to some extent, such as: Compensate for slightly elevated carbon dioxide levels. However, these measures may come at the expense of other functions such as osmoregulation. Compensation also depends on the health of the gill epithelium and other environmental factors such as external sources of nitrogen and ammonia that may increase depending on future culture orientation and degree of eutrophication. Fish can also remodel their gill structure in response to salinity, hypoxia, or acidification, although elevated temperatures may be associated with increased pathology seen in the gills, and may be associated with specific Fish may be more susceptible to change. More focused research on climate-change-specific gill physiology and recognition of gill health as an important component of food security, not just fish health. Another common use of dramatic tail fin changes, often in conflict with striking locomotion, is cueing. Tall dorsal fins, filaments, flourishes, and dramatic coloration help signal (or remain unnoticed) to mates, rivals, and predators. Warning coloring and mating indications can be worn on the fin surfaces as needed, as the pectoral fins can be flapped and color signals can be flashed at will. In such competitive marine environments, the utilization of fin modifications has repeatedly improved fish species fitness, creating both beautiful and bizarre morphologies across diverse marine fish trees. To understand the impact of projected climate change on fish health, understanding what gill health is and what it affects is probably a good starting point. A central tenet of homeostasis in most health sciences is the need to maintain physiological function within a safe operating range in the face of stressors. The importance of gills in fishing and how far you can stretch your limits before health is compromised is not well understood. Aristotle (350 BC), in his animal history, described the gills of fish as "extraordinary organs," but the true versatility of the fish gills was not established until the late 19th and early 20th centuries. It wasn't until Fishes are the most diverse group of vertebrates on Earth, with about 25,000 species, all of which have marked anatomical and physiological differences at different latitudes and in different niches. Lifestyle, active or sedentary, and physico-chemical environment such as temperature, oxygen, salinity, turbidity and ammonia. The link between fish health and gill health is not always immediately obvious, and measuring gill health can be problematic. Even in veterinary medicine, finding a definition of health is surprisingly difficult. A very simple definition of health in veterinary medicine is essentially a dichotomy: the presence or absence of disease. This is a common finding in epidemiological studies, where disease incidence is often calculated based on whether an animal or population dies from the disease.