CRISPR/Cas9 Technology for Enhancing Desirable Traits of Fish Species in Aquaculture.

Aquaculture, the world's fastest-growing food production sector, is critical for addressing food security concerns because of its potential to deliver high-quality, nutrient-rich supplies by 2050. This review assesses the effectiveness of CRISPR/Cas9 genome editing technology in enhancing desirable traits in fish species, including growth rates, muscle quality, disease resistance, pigmentation, and more. It also focuses on the potential effectiveness of the technology in allowing precise and targeted modifications of fish DNA to improve desirable characteristics. Many studies have reported successful applications of CRISPR/Cas9, such as knocking out reproductive genes to control reproduction and sex determination, enhancing feed conversion efficiency, and reducing off-target effects. Additionally, this technology has contributed to environmental sustainability by reducing nitrogen-rich waste and improving the nutritional composition of fish. However, the acceptance of CRISPR/Cas9 modified fish by the public and consumers is hindered by concerns regarding public perception, potential ecological impacts, and regulatory frameworks. To gain public approval and consumer confidence, clear communication about the editing process, as well as data on the safety and environmental considerations of genetically modified fish, are essential. This review paper discusses these challenges, provides possible solutions, and recommends future research on the integration of CRISPR/Cas9 into sustainable aquaculture practices, focusing on the responsible management of genetically modified fish to enable the creation of growth and disease-resistant strains. In conclusion, this review highlights the transformative potential of CRISPR/Cas9 technology in improving fish traits, while also considering the challenges and ethical considerations associated with sustainable and responsible practices in aquaculture.

Genetic diversity of the common carp black strain population based on mtDNA (D-loop and cytb).

The common strain black carp (Cyprinus carpio var. baisenensis) is a culturally important carp strain that is raised and cultured in Guangxi Province, China. Its color reflects the interactions between the Burau people and their surrounding environment. The population of the common carp black strain was isolated and cultured in a rice-fish integration system. To explore the genetic diversity and protection of germplasm resources, we analyzed mitochondrial DNA (mtDNA) sequences, specifically the displacement loop (D-loop) and cytochrome b (Cytb), using single-nucleotide polymorphisms (SNP). We compared these sequences with those from four other local common carp populations. The study included a total of 136 adult common carps from five strain populations: the common black carp strain (HJ = 31), Jian (F = 30), Heilongjiang (H = 10), Songpu (S = 31), and Saijiang (SJ = 34). The results of the Cytb and D-loop analyses showed that the Heilongjiang carp (H) and Saijiang (SJ) populations had the highest levels of haplotype diversity (0.867 ± 0.034785) and nucleotide diversity (π = 0.0063 ± 0.000137 and 0.0093 ± 0.000411), respectively. On the other hand, the Common carp black strain population (HJ) exhibited the lowest haplotype diversity in both Cytb and D-loop, with haplotype 2 being the most commonly observed among the populations. Private haplotypes dominated the five common carp populations, which were significantly different at P<0.001. Furthermore, analyzing the coefficient of genetic differentiation (Fst), the highest genetic difference was observed between Saijiang (SJ) and Heilongjiang (H) (Fst = 0.963), whereas the lowest was observed between Songpu (S) and the Common carp black strain population (HJ) (Fst = 0.019) for the Cytb gene sequences. For the D-loop, the Common carp black strain population (HJ) and Songpu (S) (Fst = 0.7) had the highest values, and Heilongjiang (H) and Common black carp strain (HJ) had an Fst of 0.125. Additionally, the AMOVA analysis revealed a higher level of variance for the Cytb and D-loop genes, indicating lower genetic diversity within the local carp community. On the other hand, the phylogenetic tree analysis showed that the five carp populations were closely related and formed a distinct cluster. The distinct cluster of populations suggests a common ancestor or recent gene flow, possibly due to geographic proximity or migration history, and unique genetic characteristics, possibly due to adaptations or selective pressures. The results of this study provide valuable insights into the genetic diversity of the common strain black carp, which can have implications for conservation, breeding programs, evolutionary studies, and fisheries management.

Effect of Dietary Selenium on the Growth and Immune Systems of Fish.

Dietary selenium (Se) is an essential component that supports fish growth and the immune system. This review attempts to provide insight into the biological impacts of dietary Se, including immunological responses, infection defense, and fish species growth, and it also identifies the routes via which it enters the aquatic environment. Dietary Se is important in fish feed due to its additive, antioxidant, and enzyme properties, which aid in various biological processes. However, excessive intake of it may harm aquatic ecosystems and potentially disrupt the food chain. This review explores the diverse natures of dietary Se, their impact on fish species, and the biological methods for eliminating excesses in aquatic environments. Soil has a potential role in the distribution of Se through erosion from agricultural, industrial, and mine sites. The research on dietary Se's effects on fish immune system and growth can provide knowledge regarding fish health, fish farming strategies, and the health of aquatic ecosystems, promoting the feed industry and sustainable aquaculture. This review provides data and references from various research studies on managing Se levels in aquatic ecosystems, promoting fish conservation, and utilizing Se in farmed fish diets.