The importance of using genetically improved strains of fish that are resistant to disease is elaborated. The reasons why aquaculture in general is still lagging behind in using genetically improved strains of fishes are discussed. Examples of genetically improved aquatic species that are cultured globally are presented. The prerequisites for initiating a genetic improvement program are highlighted, citing examples from aquatic species. The genetic basis for disease resistance is discussed with examples both from India and globally. The progress made in India, especially with regard to freshwater species, such as carps and scampi, is discussed. The shrimp industry of India today depends on an imported selectively bred strain of Pacific white shrimp for commercial culture and export, a species that dominates even the global shrimp industry in terms of production. Genomic research carried out in tiger shrimp and carp in India is detailed. While the selection of individuals for breeding utilizes computed breeding values, there appears to be a higher advantage when genomic information is incorporated into the selection process. Instances of genetics and genomics aiding selection programs in Atlantic salmon and Genetically Improved Farmed Tilapia (GIFT) are also explained. The advantages of using strains of fish genetically improved for disease resistance and advanced genomic tools, such as CRISPR for gene editing, as future methods to improve disease resistance in fish are elucidated.