1. Core Scope of Fish Genetics

Traditional fish genetics centers on heritability and variation of fish traits at individual and population levels:

Mendelian & quantitative geneticsIt analyzes the inheritance patterns of key economic traits including growth rate, body shape, meat yield, cold tolerance, disease resistance and body color. Most productive traits of fish belong to quantitative traits controlled by multiple minor-effect genes, which is the theoretical basis for selective breeding, family breeding and cross breeding.

CytogeneticsStudies fish chromosome number, karyotype, ploidy variation and sex-determination systems. Many fish exhibit diverse sex-determining modes (XY, ZW, polygenic sex determination), and polyploid induction, gynogenesis and androgenesis technologies derived from cytogenetics are widely used to establish pure lines and sterile varieties.

Population & evolutionary geneticsReveals genetic diversity, population genetic structure, gene flow and differentiation time of wild and farmed fish populations via molecular markers (SSR, SNP, mitochondrial genes). It clarifies biogeographic evolution, germplasm resource differentiation and genetic degradation risks caused by overfishing and inbreeding.

2. Research System of Fish Genomics

With the development of high-throughput sequencing, genomics has become the mainstream research tool in aquatic science, covering multiple omics dimensions:

Reference genome assemblyPacBio HiFi and ONT long-read sequencing combined with Hi-C technology are applied to assemble chromosome-level complete genomes of economic fish (such as largemouth bass, common carp, grass carp). High-quality reference genomes provide fundamental maps for gene location and functional excavation.

Functional genomics

Transcriptomics: Compares gene expression differences under different feeding, temperature and pathogen stress to screen genes related to growth, immunity and stress resistance;

Proteomics & metabolomics: Explains the protein and small-molecule metabolic regulatory network behind phenotypic changes;

Gene editing (CRISPR/Cas9): Verifies gene functions by knockout or overexpression, accelerating the identification of major genes controlling economic traits.

Comparative & evolutionary genomicsCompares genome structure, gene family expansion/contraction, collinear relationship and conserved non-coding sequences among different fish taxa, revealing adaptive evolution mechanisms such as freshwater-saltwater adaptation, hypoxia tolerance and skeletal development.

Selective sweep & molecular marker developmentGenome-wide association study (GWAS) and selective sweep analysis locate SNP loci and candidate genes associated with target traits. High-density SNP chips and molecular markers are developed for genomic selection (GS), greatly improving breeding efficiency compared with traditional phenotype-based selection.

3. Key Application Directions

Precision genetic breeding of aquaculture speciesGenomic selection accelerates the breeding of new varieties with fast growth, high survival rate and strong disease resistance, such as improved largemouth bass strains, carps and tilapia, reducing feed cost and breeding loss.

Protection and evaluation of wild fishery germplasm resourcesGenomic data assess the genetic integrity of wild populations, formulate germplasm protection strategies, and distinguish wild individuals from escaped farmed fish to avoid genetic pollution.

Aquatic disease controlMining immune-related genes and disease-resistant molecular markers to cultivate disease-resistant fish strains and reduce antibiotic usage in aquaculture.

Evolutionary and developmental basic researchFish represent the largest vertebrate group; genomic research on teleosts uncovers vertebrate origin, whole-genome duplication events and the molecular mechanism of special morphological traits (intermuscular bones, body color, fin shape).

4. Research Significance

As global aquaculture expands continuously, fish genetics and genomics solves critical bottlenecks including slow breeding progress, germplasm degradation and frequent aquatic diseases. It realizes the transformation of fishery breeding from conventional phenotypic selection to genome-informed intelligent breeding, guarantees the sustainable development of aquatic seed industry, and also provides vital model data for general vertebrate genetic and evolutionary research.