Reproduction and development in some species of the weakly electric genus Campylomormyrus (Mormyridae, Teleostei)

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• 作者：Linh Nguyen ; Christiane Paul ; Victor Mamonekene…
• 关键词：Campylomormyrus ; Cyclical reproduction ; Environmental factors ; Behavior ; Ontogeny ; Artificial reproduction
• 刊名：Environmental Biology of Fishes
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：100
• 期：1
• 页码：49-68
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Freshwater & Marine Ecology; Zoology; Animal Systematics/Taxonomy/ Biogeography; Environment, general; Nature Conservation;
• 出版者：Springer Netherlands
• ISSN：1573-5133
• 卷排序：100

文摘

Reproduction in captivity of four species of the mormyrid genus Campylomormyrus was investigated. Cyclical reproduction was provoked by changing water conductivity (C) alone: decreasing C led to gonadal recrudescence, an increase induced gonad regression. Data on the reproduction and development of three species are presented. All three species are indeterminate fractional spawners. Spawning intervals ranged from 6 to 66 days in C. rhynchophorus, 10–75 days in C. tshokwe, and 18 days in C. compressirostris (calculated values). Fecundities (eggs per fractional spawning) ranged from 70 to 1570 eggs in C. rhynchophorus, 100–1192 in C. tshokwe, and 38–246 in C. compressirostris. Spawnings/ovipositions occurred during the second half of the night; no parental care was observed; no special spawning substrates were necessary. C. compressirostris successfully spawned in breeding groups, C. rhynchophorus as pair. Agonistic behavior in the C. tshokwe pair forced us to divide the breeding tank; therefore, only ovipositions occurred. However, injection of an artificial GnRH hormone allowed us to obtain ripe eggs and sperm and to perform successful artificial reproduction. All three species produce yolky, slightly sticky eggs. Egg diameter ranges from 2.3–3.0 mm. Hatching occurred on day 3, feeding started on day 11. Transition from larval to juvenile stage occurred at around 20 mm total length (TL). At this size C. rhynchophorus developed a higher body than the two other species and differences between the species in the melanin pigmentation of the unpaired fins occurred. Between 32 and 35 mm TL the upper and lower jaws started to elongate.