The challenge of feeding a growing global population while minimizing environmental impacts is particularly pressing in developing countries. The demand for animal protein is expected to rise, exacerbating environmental challenges like droughts and floods. Increasing fish and seafood consumption, particularly through aquaculture can serve as a potential solution. The aquaculture industry, crucial for livelihoods and food security, faces risks from disease outbreaks due to intensified production. Environmental factors like water quality and climate change further heighten these risks, making fish more susceptible to bacterial pathogens, which can cause significant economic and ecological damage. Advances in molecular diagnostic techniques for detecting fish pathogens offer promising solutions for managing these risks. These techniques, which include DNA sequencing and PCR can allow for faster and more accurate diagnosis of diseases, in comparison to traditional culture methods. However, widespread adoption of these methods requires validation and integration into routine diagnostic practices. Disease prevention in aquaculture focuses on maintaining a healthy environment through proper sanitation, chemo-prophylaxis, vaccination, and environmental manipulation. Treatment methods vary depending on the situation, including the use of chemicals in water, feed, or direct application to f ish. The success of fish production depends on the health of species, making disease monitoring and management crucial. Despite progress in diagnostic techniques, there are a few of challenges, such as variability of disease symptoms, involvement of multiple pathogens, and human error in diagnosis. To ensure the effectiveness of new molecular methods, large-scale validation and trials are needed. These efforts will be essential for advancing fish health management and sustaining aquaculture production in the face of growing global demand and environmental pressures. The initiative by ICAR-CIFRI to publish the book entitled "Fish Disease: Diagnosis and Treatment" with an innovative approach is commend-able. We believe this book will set a significant benchmark in addressing fish diseases and their prevention.

A key challenge for the years to come is feeding a rapidly growing human population while lowering the impact of food production on the environment. This is particularly true for low and middle-income countries where the demand for animal protein is likely to rise and further increase several folds in existing environmental changes (e.g., droughts, floods, extensive wildfires) have in recent years led to major food crises. To achieve these goals, food production not only needs to be increased, but most of all, good husbandry practices must be followed to reduce its negative impacts on the environment. Several studies have suggested that shifting the human diet towards increased consumption of f ish and seafood could be a solution to the need for protein that would sustain human and environmental health. In fact, fish and seafood consumption is forecast to increase by 27% on the horizon of 2030, mostly sustained by the aquaculture sector, which is expected to grow by 62% during the same period. The aquaculture industry contributes significantly to livelihood, food security, and poverty alleviation, with over 100 million people estimated to rely on aquaculture for their living. Fish is a cheap source of animal protein, and the current per capita consumption of fish in India is around 9 kg per annum, which is compared to the 11 kg recommended by the World Health Organisation (WHO). Presently, the contribution of the fisheries sector to the gross domestic product (GDP) and agriculture GDP has been estimated to be 1.2 and 4.2%, respectively.

Clinical Symptoms • Gasping for air • Discoloured gills with trapped materials • Swollen gills with enhanced mucous secretion • White to grey spots on the gills • Diseased fish gather near the outlet of the pond • Fish become lethargic and remain on the surface waters Causative Agent: Flavobacterium branchiophilum, Cytophaga spp., Flexibacter spp. Host (Common sp.) • Goldfish • Koi carp • Cichlids • Fighter fish • Gourami fish

Clinical Symptoms • External haemorrhages • Pale gills • Ascites • Destruction of tissues in the kidney, spleen, and liver • Excessive mucus secretion • Skin hemorrhages with edema of the tissues • Skin ulceration around the mouth and base of the fins Causative Agent: Rhabdovirus Host (Common sp.) • Common carp • Koi carp • Crucian carp • Silver carp • Bighead carp • Grass carp • Goldfish

Clinical Symptoms • Anchor worms can be seen with the naked eye • Frequent rubbing or “flashing” • Localised redness • Inflammation on the body of the fish • Tiny white-green or red worms in wounds • Breathing difficulties

Clinical Symptoms • White/brown cotton-like foci on the surface of the skin and/or gills • Peritonitis • Extensive haemorrhage • Necrosis • Adhesions