Morphological Variation between Hatchery Bred and Wild Caught Anabas testudineus in Malaysia.

This study was designed to characterise the cultured and wild populations of Anabas testudineus in Malaysia using morphological parameters. Fish samples from the East and West coast of the country were obtained from fishermen (wild samples) and well-recognised climbing perch farmers in Kedah, Kelantan, Johor and Selangor. The Truss network method was applied to obtain necessary data and analysed to examine phenotypic variation between the cultured and wild stocks. Results obtained suggest that each hatchery population belonged to a distinct stock as revealed by their separate clustering into individual unique groups. However, an extensive overlap was observed in the wild population suggesting similarity of origin. The most important morphological parameters for the discrimination of the two populations are the homologous landmark B (i.e., snout to insertion of the pelvic fin) and C (i.e., above the eye to insertion of the pelvic fin). Genetic characterisation of the A. testudineus is needed to complement the findings of this study and establish a baseline for the development of a selective breeding programme for the fish species in Malaysia.

Kajian ini dijalankan untuk mencirikan populasi Anabas testudineus yang dikultur dan liar di Malaysia menggunakan parameter morfologi. Sampel ikan dari pantai timur dan barat negara ini diperoleh daripada nelayan (sampel liar) dan penternak ikan yang diiktiraf di Kedah, Kelantan, Johor dan Selangor. Kaedah rangkaian Truss digunakan untuk mendapatkan data yang diperlukan dan dianalisis untuk memeriksa variasi fenotip antara stok kultur dan liar. Keputusan yang diperoleh menunjukkan bahawa setiap populasi penetasan tergolong dalam stok yang berbeza seperti yang didedahkan oleh kelompok berasingan ke dalam kumpulan unik individu. Walau bagaimanapun, pertindihan yang luas diperhatikan dalam populasi liar yang mencadangkan persamaan asal. Parameter morfologi yang paling penting untuk diskriminasi kedua-dua populasi ialah mercu tanda homolog B (iaitu, snout untuk memasukkan sirip pelvis) dan C (iaitu, di atas mata untuk memasukkan sirip pelvis). Pencirian genetik A. testudineus diperlukan untuk melengkapkan penemuan kajian ini dan mewujudkan asas untuk pembangunan program pembiakan terpilih untuk spesies ikan di Malaysia.

Microalgal Preference and Feeding Density of Selected Microalgae Diets by Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758).

<b>Background and Objectives:</b> Blue swimming crab, <i>Portunus pelagicus</i> (Linnaeus, 1758) are economically important sources of soft-shell products for export demand. However, increasing over-exploitation and pollution towards the sea resources affected the production of the <i>P. pelagicus</i>. The study aimed to determine the microalgal preference and feeding density of the monospecific (<i>Nannochloropsis oculata</i>, <i>Chlorella vulgaris</i>, <i>Isochrysis galbana</i> and <i>Chaetoceros wighamii </i>) by individual <i>P. pelagicus </i>larvae. <b>Materials and Methods:</b> In the microalgal preference study, one polystyrene tray with 100 holes was set up in the experimental tank (200 L) to place the 50 mL centrifuges tube. For feeding density study, the survival rate, Specific Growth Rate (SGR), Body Weight (BW) and Larvae Stage Index (LSI) of each larvae stage were collected from Zoea 1 (Z₁) till megalopa. <b>Results:</b> Results for mean microalgal preference of individual larvae preferred most <i>Chlorella vulgaris</i> during Zoea 1 and 2, the larvae consumed the highest of <i>Nannochloropsis</i> <i>oculata</i>. For Zoea 3 and 4, the highest preference is <i>Isochrysis galbana</i>. For feeding regime, Zoea 1, larvae fed rotifer, <i>Artemia</i> and <i>Chlorella vulgaris</i> (T₃), was the highest survival rate, Zoea 2 was larvae fed rotifer, <i>Artemia</i> and <i>Nannochloropsis oculata</i> (T₅) and both Zoea 3 and Zoea 4, larvae fed rotifer, <i>Artemia</i> and <i>Isochrysis galbana</i> (T₄) was the highest survival rate. The highest SGR and LSI were obtained in T₄ cultured in 14 days. <b>Conclusion:</b> In conclusion, the microalgal preference and feeding density of the selected microalgae are different depending on each larvae stage.

Fillet Yield and Length-Weight Relationship of Five Fish Species From Lower Benue River, Makurdi, Nigeria.

The body characteristics and yield indices of Clarias gariepinus, Bagrus bajad, Synodontis nigrita, Labeo senegalensis and Mormyrus rume from lower Benue River in Nigeria were determined in this study using 60 samples each for the fish species. Length, weight and fillet correlations were also determined during the study. Results obtained showed that M. rume, L. senegalensis and C. gariepinus had the highest percentage of edible parts (≥ 55%) compared to the other species (≤ 39%). Concerning correlations of the fillet with the morphological variables, results obtained suggest that fillet yield is independent of fish size (except for C. gariepinus which was positively correlated). Also, only samples of L. senegalensis showed isometric growth pattern; the other fish species had either positive (C. gariepinus and B. bajad) or negative (S. nigrita and M. rume) allometric growth. While the difference in fillet yield and body characteristics was attributed to the structural anatomy and other biological dynamics of the fishes, this study could not establish a connection between fillet yield and the length-weight relationship. It was concluded that M. rume, L. senegalensis and C. gariepinus would be better export products because of their higher fillet yields.