Evaluation of growth, sex (male proportion; sexual dimorphism), and color segregation in four cross combinations of different strains of XX female and YY male Nile Tilapia

Abstract

Four cross combinations of different YY male and female Nile Tilapia Oreochromis niloticus strains were evaluated for growth, sex, and color segregation. Red color parental strains included blotched phenotypes. The Genetically Improved Farmed Tilapia (GIFT) was the only dark (wild‐type) color parental strain. Fish of the same age and cross were stocked in three replicate tanks for four crosses in one recirculating system for 167 days. Data recorded included feed consumed, body weight, total length, color, sex, and fillet weight. YY males crossed with GIFT females (Cross 2) exhibited superior growth that was significantly different (p < .05) to other three crosses. Male proportions were 79–100%. Only YY males crossed with the LSA female strain (Cross 4) yielded 100% males, but, Cross 4's productivity was inferior to that of Cross 2. Body weight advantage of males over females was 28.7–84.2%. Color segregation indicated that red color trait in Nile Tilapia is autosomal dominant, and black patch coverage was variable. This study showed that different parental strain combinations clearly impact productivity traits, and that YY male technology combined with crossbreeding provide the opportunity for genetic improvement and development of commercially beneficial superior traits in Nile Tilapia.

Genetic Variability of Nile Tilapia Strains as Determined by Microsatellite DNA Markers

“…Recently, Novelo et al (2021) reported the results of a study evaluating growth and other traits in four cross combinations of different YY‐male and female Nile Tilapia strains. In that study, the dependence of a cross’s productivity on genetic differentiation between its parental strains, as determined based on the SNP data obtained by Delomas et al (2019), was investigated.…”

Polymorphism in a sex‐linked DNA marker located on LG23 in Hainan strain of Nile tilapia (Oreochromis niloticus)

“…Previous studies have shown that Nile tilapia has an XX/XY male heterogametic system for sex determination, which is controlled by a major gene (Mair, Scott, Penman, Beardmore, & Skibinski, 1991). Based on crosses between XX females and YY males, researchers have developed genetically male tilapia (GMT) technology, an effective method for the large-scale production of all-male tilapia (Mair et al, 1995;Novelo, Gomelsky, Coyle, & Kramer, 2020). The fast and accurate identification of the sex genotype is critical for this method.…”

Diallel Hybridization of Oreochromis niloticus (Nile Tilapia) to Oreochromis aureus (Blue Tilapia)

“…At a certain time in Southeast Asia, tilapia is regarded as weed fish (fish to be eliminated) before stocking the folk's fish as a result of the fish not reaching market size in culture . However, the ability of the male fish to reach market size on time made it possible for breeders to focus on raising monosex tilapia with a focus on the male fish because tilapia exhibit sexual dimorphism (Novelo et al, 2020).…”