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Baras E.,IRD Montpellier | Slembrouck J.,IRD Montpellier | Priyadi A.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Satyani D.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | And 2 more authors.
Aquatic Living Resources | Year: 2012

Hatchlings of clown loach (3.8 mm in total length, TL) are pelagic. When reared at 26-28°C, they become benthic 3 days after hatching (dah), when their swim bladder is inflated. The fin development sequence (pectorals < caudal < dorsal = anal < pelvic) is typical of the clade Ostariophysi. All fins and finrays are fully elongated at 20 mm TL, but the finfold persists until 25-26 mm TL (start of juvenile stage). Melanophores appear at 3 dah, they form a 5-bar pattern at 5 dah, then two bars (III and V) vanish progressively, producing at 26 mm TL the 3-bar pattern that is typical of adults. Throughout the ontogeny, the pigment pattern exhibits a structural regularity (bars spaced at regular intervals), which is interpreted in a functional perspective by reference to the maintaining of crypsis and signalling throughout. Exogenous feeding commences at 4 dah (5.5 mm TL). Food intake (FI) increases rapidly, from 6% wet body mass (WM) at 5.5 mm TL to >20% WM in fish > 7 mm TL. Gut evacuation rate (Rg) increases with increasing meal size and fish size, as a result of gut coiling (from 8 to 15 mm TL), and is highest at 11 mm TL (about 10% WM h-1 in fish feeding maximally). The allometric increase of FI and Rg during the early larval stages is accompanied by increasing capacities for growth, so early sizes differences amplify rapidly during the ontogeny. Nevertheless, growth remains slow (mean of 0.4 mm TL day-1 from 4 to 29 dah; 0.9 mm TL day-1 for top growers). By contrast, unfed fish display long resistance to starvation (until 14-15 dah). The combination of slow growth and long resistance to starvation is discussed in respect to the reproductive phenology of the species, as the capacity of making metabolic economies prevails over fast growth for seasonal strategists spawning mainly at the start of the rainy season. © 2012 EDP Sciences, IFREMER, IRD.

Legendre M.,IRD Montpellier | Satyani D.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Subandiyah S.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Sudarto,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | And 3 more authors.
Aquatic Living Resources | Year: 2012

The clown loach Chromobotia macracanthus, endemic to Indonesia, is a major species on the international market of ornamental freshwater fish. In order to satisfy an increasing demand with a sustainable alternative to the massive capture of wild juveniles, research has been dedicated to the artificial propagation and domestication of this species. The present study, the first of a series, focused on favourable maintenance conditions for broodfish sexual maturation, criteria for identification of ripe fish, efficiency of hormone-induced breeding treatments, predictability of their latency response, and on the comparison of reproductive performances of fish from populations of Sumatra and Borneo Islands (in total, 112 females of 46 to 404 g body weight). When reared in fully controlled conditions in large water recirculation systems, broodfish originating from Sumatra had reproductive performances similar to or slightly higher than those maturing in the wild (ovulation rate of 93% vs. 82%, relative fecundity of 109 277 vs. 103 550 ova kg-1 and fertilization rate of 73% vs. 61%, respectively). In the same rearing conditions, captive females from Borneo (n = 22) showed lower ovulation rate (77%), relative fecundity (76 262 ova kg-1) and fertilization rate (50%) than those originating from Sumatra (n = 28). By contrast, the mean individual weight of ova (around 0.8 mg) was independent from the origin or maintenance conditions of females. An initial modal follicle diameter 1.02 mm generally led to high ovulation success (<80%) after hormonal treatment and is recommended as the main criterion for selecting female broodfish. Two hormonal treatments for inducing oocyte maturation and ovulation (T1: two successive injections of Ovaprim at a 6 h-interval; T2: one injection of human chorionic gonadotropin (hCG)-and one of Ovaprim 24 h later), produced similar results in terms of ovulation rate, quantity and quality of ova collected. With both treatments, the latency decreased with increasing water temperature, then increased again at temperatures <28-29 C. To our knowledge, such U-shaped relationship between the latency response and temperature has never been documented in teleost fishes. © 2012 EDP Sciences, IFREMER, IRD.

Baras E.,IRD Montpellier | Ginanjar R.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Ahmad M.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Permana A.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | And 4 more authors.
Aquatic Living Resources | Year: 2012

The knowledge of how fish survive and grow at different temperatures, and how these traits vary between life stages, is essential to evaluate the effects of climate change on wild fish and implement effective strategies in aquaculture. These issues are addressed in this study through a series of experiments that evaluate the effect of temperature (23-34°C) on the embryos and larvae of clown loach, Chromobotia macracanthus. This species is endemic to the rivers of Sumatra and Borneo, highly praised on the ornamental fish market, and has been reproduced in captivity recently. No embryo survived a 24-h exposure to 34°C until the age of 3 days after hatching (dah); mortality was high at 32°C at 2 and 3 dah, whereas it was low and similar from 1 to 4 dah at 23-29°C (<10%). Yolk absorption was proportional to water temperature (Q10°C Q10 °C} Q 10 C of 1.69 in the 23-32°C range), but fish reared at cold temperatures were larger than others at the start of exogenous feeding (5.7 vs. 5.5 mm TL, at 23 and 32°C, respectively). The survival of larvae fed Artemia nauplii ad libitum was high at 23-32°C (80-100%), but almost null at 34°C. Growth models at different temperatures were produced from weekly measurements in two experiments, and tested by comparing their predictions with the results of a third experiment. Throughout the larval stage, the optimal temperature for growth (T°opt) Topt} T opt) was close to 29°C, and departures from T°opt Topt} T opt resulted in substantial growth penalties (-30% SGR for-5.1°C and + 3.1°C). High survival, fast growth (0.7 mm day-1) and limited size dispersal at T°opt Topt} T opt are encouraging perspectives for the aquaculture of clown loach. From an ecological perspective, the species has an atypical thermal biology, as it is less thermophilic than other tropical fishes, but more stenothermal than temperate fishes exhibiting similar values of T°opt Topt T opt, both traits being of particular concern in the context of global warming. © 2012 EDP Sciences, IFREMER, IRD.

Slembrouck J.,IRD Montpellier | Priyadi A.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Permana A.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | Ginanjar R.,Balai Penelitian Dan Pengembangan Budidaya Ikan Hias BP2BIH | And 5 more authors.
Aquatic Living Resources | Year: 2012

In comparison to older life stages, the embryonic stages of fishes generally have narrow tolerance ranges for environmental conditions, as regards water quality, temperature and mechanical shocks. The knowledge of these factors is indispensable to appraise the threats brought about by climate or anthropogenic changes upon their resilience, and to define adequate ways of incubating their eggs for an efficient propagation of the species under controlled conditions. Clown loach eggs have a narrow thermal tolerance range in comparison to other tropical and temperate fishes. Hatching occurs at 22-30 °C, and non-deformed larvae can only be obtained at 23.8-30.2°C. Furthermore, the thermal tolerance of any particular progeny was found dependent on the maintenance temperature of the female parent, thereby making the actual tolerance no broader than 4.5°C. The (log-log) relationship between the duration of the incubation period and temperature was characterized by a shallow slope, which is more typical of coldwater fishes, as is a narrow thermal tolerance range. On the other hand, clown loach hatched more rapidly (20 h at 26°C) than predicted by existing models on the basis of water temperature and egg diameter, a feature that is shared by other warmwater fishes producing eggs that undergo a strong swelling process (about three times the ova diameter in clown loach). Clown loach embryos are strongly sensitive to mechanical shocks, but their development is not viable either in protracted steady state conditions, in absence of water movement, as they develop various deformities (e.g. pericardial oedema). This is thought to originate from a hypoxic microenvironment around the embryo, as a consequence of an oxygen gradient developing inside and outside the egg, since the boundary diffusion layer is not refreshed by water movement. This issue is worsened by strong egg swelling and incubation at warm temperature. © 2012 EDP Sciences, IFREMER, IRD.

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