Induction of triploidy and economic traits analysis in large yellow croaker (Larimichthys crocea)

Triploid, a key strategy for reproductive control, its comprehensive effects for Larimichthys crocea remain to be elucidated. This study achieving 100% triploid via cold treatment. Using offspring from a single parental pair and rearing in adjacent, non-replicated net pens within an integrated cage system, providing a controlled comparison between triploid and diploid siblings under synchronized environmental conditions. Hatching rates did’t differ ( p = 0.15). At 20 months post-hatch (mph), diploid reproductive season: stage V in testes ovaries, triploids exhibited impaired gametogenesis: testes stage III; ovaries stage I, leading higher carcass yield (92.93 ± 0.83% vs. 90.33 ± 3.35%, p < 0.01), reduced gonadosomatic index (0.58 ± 0.23 vs. 3.45 ± 3.14, p < 0.001), 27.05% enhanced body weight uniformity. However, a phenotypic trade-off was observed. Triploid weight was comparable to diploid males ( p = 0.71) but lower than diploid females (406.33 ± 129.26 g; p < 0.05), suggesting triploidization eliminates the female-specific growth advantage by suppressing sexual dimorphism rather than generalized growth impairment. Furthermore, triploids showed similar resistance to Cryptocaryon irritans ( p = 0.059) at 132 days post-hatch (dph), lower tolerance to Vibrio alginolyticus (14.82% vs. 21.76%, p < 0.05) at 151 dph, and lower relative swimming speed (BL/s) (2.50 ± 0.39 vs. 3.12 ± 0.42, p < 0.05) at 13 mph. These results indicate triploidization balances gains in reproductive control, carcass yield, uniformity against loss of sex-specific growth increments, bacterial disease resistance, and swimming stamina, providing a practical framework for evaluating the commercial and ecological suitability of triploid L. crocea . • Cold treatment achieved 100% triploid induction in Larimichthys crocea under commercial hatchery conditions. • First large-scale performance evaluation of triploid individuals across juvenile-to-adult stages in large yellow croaker. • The first evidence of gonadal developmental impairment in adult triploid large yellow croaker. • Market-size triploid showed higher carcass yield and reduced gonadal investment despite sex-dependent weight differences.