213 https://www.e-fas.org Fisheries and Aquatic Sciences RESEARCH ARTICLE Fish Aquat Sci. 2024;27(4):213-224 https://doi.org/10.47853/FAS.2024.e21 eISSN 2234-1757 Received: Nov 7, 2023 Revised: Dec 7, 2023 Accepted: Dec 20, 2023 *Corresponding author: Darmawan Setia Budi Study Program of Aquaculture, Department of Health and Life Sciences, Faculty of Health, Medicine, and Life Sciences, Universitas Airlangga, Banyuwangi 68425, Indonesia Tel: +62-333-417788, Fax: +62-333-428890, E-mail: darmawansetiabudi@fpk.unair.ac.id is is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by- nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright © 2024 e Korean Society of Fisheries and Aquatic Science Captive breeding of endangered betta fish, Betta rubra, under laboratory conditions Agus Priyadi 1 , Asep Permana 1 , Eni Kusrini 2 , Erma Primanita Hayuningtyas 2 , Bastiar Nur 2 , Lukman 1 , Josie South 3 , Sawung Cindelaras 2 , Sulasy Rohmy 2 , Rendy Ginanjar 1 , Muhamad Yamin 2 , Djamhuriyah S Said 4 , Tutik Kadarini 2 , Darmawan Setia Budi 5, * 1 Research Center for Conservation of Marine and Inland Water Resources, National Research and Innovation Agency, Jakarta 10340, Indonesia 2 Research Center for Fishery, National Research and Innovation Agency, Jakarta 10340, Indonesia 3 School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK 4 Research Center for Limnology and Water Resources, National Research and Innovation Agency, Jakarta 10340, Indonesia 5 Study Program of Aquaculture, Department of Health and Life Sciences, Faculty of Health, Medicine, and Life Sciences, Universitas Airlangga, Banyuwangi 68425, Indonesia Abstract Betta rubra, classified as endangered fish species by the International Union for Conservation of Nature (IUCN), has been success- fully bred and raised in captivity for two generations under laboratory conditions. This study aimed to provide comprehensive information on the captive breeding of B. rubra, focusing on various parameters crucial for ex-situ conservation and domestica- tion. The research involved breeding trials, embryo and larvae observation, first feeding experiments, larva and fry rearing trials, and the evaluation of growth and reproduction in two generations. The study revealed that the female B. rubra, with an average total length of 5.17 ± 0.15 cm and weight of 1.61 ± 0.06 g, produced an average of 73.67 ± 7.09 eggs, 34.33 ± 5.13 total larvae, and exhibited a hatching rate of 46.67 ± 5.77%. The embryogenesis process commenced on the day of spawning (dps) and con- tinued until the eggs hatched at 6 dps. Larvae development and yolk absorption occurred from 0 to 6 days post-hatching (dph). The study also examined the impact of different initial feeding options, with chopped Tubifex resulting in the most significant in- crease (p < 0.05) in length. The growth pattern of B. rubra larvae showed slow initial growth during the first seven days, followed by a rapid exponential growth phase from day 8 to day 39. Two generations of B. rubra (G1 and G2) were successfully bred in captivity, with G2 showing a better tendency for growth in length and weight compared to G1. Notably, there were no signifi- cant differences (p > 0.05) in reproductive success between the wild-origin broodstock (G0), G1, or G2. This research contributes valuable insights into the captive breeding of B. rubra and its early life stages, offering critical information for the conservation and sustainable management of this endangered species. Further research is needed to explore the long-term effects of domes- tication on behavior, physiology, and phenotypic diversity. Keywords: Fish species, Conservation, Captivity, Breeding, Endangered