Molecular Techniques in Diagnostic Pathology of Fish: A New Era in Aquatic Animal Health Management

The intensification of aquaculture has increased the risk of infectious diseases, creating a need for rapid and reliable diagnostic tools. Molecular techniques have transformed fish disease diagnosis by enabling sensitive and specific pathogen detection, often before clinical signs appear. This article reviews major approaches, including PCR, qPCR, ddPCR, LAMP, RPA, RAA, ERA, CRISPR-based diagnostics, DNA barcoding, FISH and molecular biosensors, highlighting their applications, advantages and limitations in aquatic animal health management. Particular emphasis is placed on the integration of isothermal amplification with CRISPR and portable detection platforms for rapid, field-deployable diagnosis. Emerging technologies such as nanopore sequencing, eDNA, metagenomics, lab-on-a-chip and smartphone-assisted diagnostics offer further opportunities for real-time disease surveillance. Despite challenges related to cost, standardization and field validation, continued advances in portable and affordable molecular diagnostics are expected to strengthen biosecurity, disease management and sustainable aquaculture.