ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Aquatic Physiology
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1613939
Combined effects of light and salinity on the growth performance in juveniles of the Malabar grouper, Epinephelus malabaricus
Provisionally accepted
- University of the Ryukyus, Nishihara, Japan
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Environmental factors, including light and salinity, influence fish growth. It has been hypothesized that optimizing environmental factors can activate the endocrine system and enhance the growth performance of fish. The aim of the present study was to understand how environmental factors affect the growth performance of juveniles of the Malabar grouper, Epinephelus malabaricus, a valuable species in Asian markets. The combined effects of light wavelength and salinity on growth performance were closely evaluated because each of them had a positive effect on growth stimulation in this species. The fish were reared under combined conditions of blue LED light (BL, 463 nm) and red LED light (RL, 623 nm) at low salinity (LS, 11psu) and high salinity (HS, 34 psu) for two weeks. Specific growth rate (SGR) was significantly higher in fish under BL/LS, followed by RL/LS and BL/HS. A higher condition factor (CF) was observed in fish under BL/LS, whereas a lower food conversion rate (FCR) was observed in fish under BL/LS and RL/LS. The transcript levels of acetyl-CoA carboxylase (acaca) and fatty acid synthase (fas) in the liver increased under BL/LS (vs. RL/LS), suggesting that the combination of these two factors activates lipogenesis. BL upregulated neuropeptide Y (npy), but not pro-opiomelanocortin (pomc), in the fish brain under both salinities, suggesting that light affects appetite. Transcript levels of growth hormone (gh) in the pituitary gland and insulin-like growth factor-1 (igf-1) in the liver were significantly lower in fish under BL/LS than in those under BL/HS. This suggests that the promotion of growth performance in juvenile Malabar groupers is attributable to the additive effects of light wavelength and salinity. Since we demonstrated the combined effects of blue light and isosmotic salinity on lipogenesis and somatic growth, optimization of light and salinity conditions can enhance the aquaculture productivity of Malabar groupers.
Keywords: Appetite, Aquaculture, Grouper, Growth, Light wavelength, Lipogenesis, Salinity
Received: 18 Apr 2025; Accepted: 13 May 2025.
Copyright: © 2025 Zhu, FUKUNAGA, Udagawa, Lu, Shimabukuro and Takemura. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Akihiro Takemura, University of the Ryukyus, Nishihara, Japan
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