The weight-length relationship, conditional factor and reproduction of the female cork fish in Sumatra, Indonesia

The characters of growth pattern and conditional factor of cork fish describe its ideal morphological condition between weight and length in various ecosystems of inland waters. Different ecosystems enable the occurrence of variation in these two characters and may affect the reproduction factor of female cork fish analyzed in this study. A total of 118 cork fish specimens were collected from nine inland waters of Sumatra, including rivers (Kampar, Merang and Batang Hari Sembilan), lakes (Ranau, Singkarak and Cala) and flood swamps (Kumpeh, Siak and Lubuk Lampam). Gonad weight, index of gonad maturity (IGM), level of gonad maturity (LGM), oocyte diameter, and the number of eggs were addressed. Data were analyzed for the relationship of weight-length using regression exponential assay, while the conditional factor and reproduction character were tested with the analysis of variance (ANOVA). The growth pattern of all populations was negative allometric (b<3), while the highest significant value of conditional factor was recorded in the population of Ranau Lake (1.63±0.1). The highest reproduction character for gonad weight was found in the population of Batang Hari Sembilan River (6.9±2.9 g), and the highest significant IGM occurred in the population of Singkarak Lake (5.6±2.7%). Whereas, the population of Lampam Swamp recorded the highest egg number (29.198±7.938 eggs). Under mature condition (LGM IV), the population of Merang River showed the largest significant diameter of the oocyte (1.26±0.5 mm) amongst all other populations; thus, they might be utilized as candidates of brood-stock for future cultivation.