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<p>This study offers preliminary insights into the early ontogeny of <i>Dawkinsia exclamatio</i>, an endangered, filament barb native to the Kerala region of the Western Ghats in India. Successful captive breeding was achieved by administering the synthetic hormone Wova-FH at a dosage of 0.3&#xa0;ml/kg body weight. Gravid males exhibited nuptial traits, including filamentous extensions on the distal tips of branched dorsal fin rays and the development of tubercles in the snout region, which were absent in mature females. Spawning occurred after a latency period of 8–9&#xa0;h, resulting in spherical, adhesive, and transparent eggs averaging 1.3 ± 0.04&#xa0;mm in diameter. Initial cleavage occurred approximately 25&#xa0;min post-fertilization, with hatching observed between 22 to 24&#xa0;h at a temperature of 26.42&#xa0;°C. The hatched yolk sac larvae measured approximately 3.31 ± 0.11&#xa0;mm in total length, featuring adhesive pear-shaped yolks lacking pigmentation. The pre-flexion larvae possessed a single-chambered swim bladder and melanophores along the body, measuring around 5.6 ± 0.07&#xa0;mm, initiating exogenous feeding on day six. The notochord flexion angle of 45 degrees and inflation of the anterior swim bladder in the larvae began on day nine. Post-flexion stage was distinguished by pelvic fin buds, a developing caudal band, emergence of dorsal fins, and rudimentary anal fin rays. The juvenile phase, the longest stage, was characterized by sub-dorsal blotches, supra-anal bands, caudal bands, and well-developed median and paired fins. Finally, the sub-adult stage, observed on day 145, exhibited the species-specific exclamation mark pattern and lacked all other juvenile markings.</p>

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Unveiling the early life of Dawkinsia exclamatio (Pethiyagoda and Kottelat 2005), an endangered filament barb from the Western Ghats: implications for conservation and sustainable use

  • 期刊论文

  • 发表日期：

    2025年3月18日

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  • Melbin Lal,
  • P. H. Anvar Ali

摘要

This study offers preliminary insights into the early ontogeny of Dawkinsia exclamatio, an endangered, filament barb native to the Kerala region of the Western Ghats in India. Successful captive breeding was achieved by administering the synthetic hormone Wova-FH at a dosage of 0.3 ml/kg body weight. Gravid males exhibited nuptial traits, including filamentous extensions on the distal tips of branched dorsal fin rays and the development of tubercles in the snout region, which were absent in mature females. Spawning occurred after a latency period of 8–9 h, resulting in spherical, adhesive, and transparent eggs averaging 1.3 ± 0.04 mm in diameter. Initial cleavage occurred approximately 25 min post-fertilization, with hatching observed between 22 to 24 h at a temperature of 26.42 °C. The hatched yolk sac larvae measured approximately 3.31 ± 0.11 mm in total length, featuring adhesive pear-shaped yolks lacking pigmentation. The pre-flexion larvae possessed a single-chambered swim bladder and melanophores along the body, measuring around 5.6 ± 0.07 mm, initiating exogenous feeding on day six. The notochord flexion angle of 45 degrees and inflation of the anterior swim bladder in the larvae began on day nine. Post-flexion stage was distinguished by pelvic fin buds, a developing caudal band, emergence of dorsal fins, and rudimentary anal fin rays. The juvenile phase, the longest stage, was characterized by sub-dorsal blotches, supra-anal bands, caudal bands, and well-developed median and paired fins. Finally, the sub-adult stage, observed on day 145, exhibited the species-specific exclamation mark pattern and lacked all other juvenile markings.