Length-weight relationship and relative condition factor of the sultan fish, leptobarbus hoevenii broodstock farmed in earthen ponds

The present study was aimed to assess the general health condition of Sultan fish, Leptobarbus hoevenii broodstock through their length-weight relationship (LWR) and relative condition factor (RCF). This broodstock was poly-cultured with the other carp’s species in earthen ponds. Totally, 95 broodstock (35 females and 60 males) were examined in this study. The total length (cm) and body weight (g) ranges of the L. hoevenii broodstock were 32.8 – 43.0 cm and 460 – 1,400 g for the females, while 30.0 – 44.5 cm and 285 – 1,300 g for the males, respectively. The b value of the females was 3.10 (> 3.0), indicating that they have attained positive allometric growth. In opposite, the males and the overall populations have attained negative allometric growth as their b value was 2.66 and 2.92 (< 3.0), respectively. All of these LWRs were significant at α = 0.01 with their correlation coefficient (r) values at 0.88 - 0.90. However, the 95% confidence interval of these b values were in the range of 2.32 – 3.64; they included 3.0 and overlapped each other. This result showed that these b values were not significantly different, indicating that the fish has achieved ideal growth. In addition, the relative condition factors of both females and males have achieved more than 1 (1.04 and 1.01, respectively), indicating that they have achieved their expected weight. Further observation on the LWR of the male L. hoevenii broodstock from the wild is necessary to confirm its optimum b value. Overall, the b value of the broodstock was 2.92 (close to 3), and their RCF value was 0.98 (close to 1). Therefore, the broodstock can be considered in good health condition. However, the influence of poly-culture management on the LWR of this broodstock should be examined in future studies

Optimization of the cytogenetic protocol for Pangasianodon hypophthalmus (Sauvage, 1878) and Clarias gariepinus (Burchell, 1822)

To obtain well spread chromosomes, the cytogenetic protocol for Pangasianodon hypophthalmus and Clarias gariepinus were optimized. This includes, the colchicine concentration (0.01%, 0.025%, 0.05%)/exposure duration (1, 3, and 5 h), hypotonic solution (distilled water or 0.075M KCl solution)/exposure duration (30 min, 1, and 2 h), the time of cell suspension preparation (at hypotonic treatment or before slide preparation) and chromosome aging period (0, 3, and 7 days in Carnoy’s fixative). In addition, the type (i.e., fin, gill or kidney) and the amount of tissue (10, 50, 100 or 150 mg) were also investigated. Regardless of the species, the result obtained showed that well-spread chromosomes could be obtained using the following optimized protocol: Juveniles are injected with 0.05% colchicine (at one ml kg−1) and allowed to swim for 3 h. Then, 50 mg of gill tissue is made into cell suspension in 0.075M KCl for 1 h. The cell suspension is treated in Carnoy’s fixative (changed three times at 20 min interval) and then aged for 3 days. Finally, chromosome slides are made and stained with 10% Giemsa for 1 h

Embryonic and larvae development of reciprocal crosses between Pangasianodon hypophthalmus (Sauvage, 1878) and Clarias gariepinus (Burchell, 1822)

The egg and larval development of reciprocal crosses of Pangasianodon hypophthalmus (Sauvage, 1878) and Clarias gariepinus (Burchell, 1822) were studied under laboratory conditions. Crosses between ♀C. gariepinus × ♂P. hypophthalmus (Clariothalmus) and ♀P. hypophthalmus × ♂C. gariepinus (Pangapinus) had embryonic stages similar to those of the pure sib, however, unequal cell cleavages were notable in the early development of both crosses, hence, leading to different forms of deformities. The critical stage where highest mortality occurred during the embryogenesis was the somite (21.68%) and hatching (48.1%) stages (respectively for the Clariothalmus and Pangapinus). However, both crosses produced viable larvae (60.21 vs 13.20% hatchability respectively), which survived (30.3 vs 2.1% respectively) until the end of the study (2 weeks). The external morphological features of the larvae were completely formed by the 14th day after hatching. The body forms of the crosses at this time were either phenotypic intermediary of the parent species (92% of Clariothalmus) or indistinguishable from the female parent (all Pangapinus and 8% of the Clariothalmus). This study thus laid the groundwork for further comparative studies on hybrid performance and characterization

Reproductive Characteristics of the Pond-Farmed Sultan Fish (Leptobarbus Hoevenii)

Highlight ResearchThe reproductive characteristics of L. hoevenii were examinedThe potentially smallest maturity sizes of female and male L. hoevenii were 350 g and 180 g, respectivelyThe fecundity of a 1,000 g L. hoevenii can be more than 100,000 eggsL. hoevenii was determined as a multiple spawnerAbstractSultan fish (Leptobarbus hoevenii) is a high value freshwater fish, cultured in some Southeast Asian countries, including Malaysia and Thailand. However, information on its reproductive characteristics is very scarce. This study examined the gonadosomatic index (GSI), fecundity, egg diameter, and determined whether L. hoevenii is a single- or multiple-spawner. Twenty male and female pond-farmed L. hoevenii broodstock were obtained to measure their total length (TL), body weight (BW) and gonad weight to calculate the GSI. Ten females were randomly sampled from the 20 to determine their fecundity. A total of 1,500 eggs were sampled from each female. The egg diameter was measured then its frequency distribution was analyzed to detect the number of egg class group, and to determine whether L. hoevenii is a single- or multiple spawner. The female L. hoevenii examined were 32.2-47.1 cm and 350-1,200 g, while the males were 30.7-45.8 cm and 180-970 g in TL and BW, respectively. All female specimens contained gonads. The potentially smallest mature samples were recorded at 350 g (female) and 180 g (male). GSI for the female and male L. hoevenii were 1.81-12.28 % and 1.03-5.09 %, respectively. The fecundity was 35,467 -128,067 eggs, while the highest fecundity was observed in a 1,000 g fish. The observed egg diameter ranged from 500 to 1,855 μm. Two to five groups of egg class were detected, indicating that L. hoevenii is a multiple spawner