Zenarchopterus buffonis

Abstract: Summary Length-weight relationships were determined for four fish species [Acentrogobius viridipunctatus (Valenciennes, 1837); Acentrogobius caninus (Valenciennes, 1837); Glossogobius olivaceus (Temminck & Schlegel, 1845); and Lutjanus ophuysenii (Bleeker, 1860)] belonging to two families. Samples were collected from 2002 to 2010 by cage net (50 × 15 × 15 cm, mesh size 0.5 cm) from Zhanjiang mangrove in China (20°36′N; 110°54′E). The total length ranged is between 2.3 and 18.1 cm and weighted between 0.3 and 90.2 g. The allometric coefficient (b) of length-weight relationship varied from 2.72 for Zenarchopterus buffonis to 3.48 for Acentrogobius viridipunctatus. Length-weight relationships for these four fish species were determined for the first time.

Abstract: Anecdotal field observations are reported for the first time for the genus Zenatr chopterus. In Z. buffonis, a species with only slightly modified male dorsal and anal fin rays, male and female swim in parallel, the male flicking the posterior body part against the female. In Z. gilli, a species with highly modified male dorsal and anal fin rays, the male swims alongside the female, folding the dorsal and anal fins in her direction, to cling to her. The function of the modified fins of male Zenarchopterus had not yet been explained, and we hypothesize that in some species with dramatic modifications, the dorsal and anal fin function as a clasping mechanism.

Abstract: The absence of a stomach in halfbeaks (Hemiramphidae) does not restrain their capability in digesting food item. Halfbeak (Zenarchopterus buffonis) is known to have a wide spectrum of dietary preference. The present study investigates the activity of four digestive enzymes along the gut of halfbeaks to determine how they digest their diets as opportunistic omnivores. A total of 20 halfbeak samples were collected from the coastal waters of Peninsular Malaysia. Overall, we found that the αamylase shows the highest enzymatic activity, followed by lipase and relatively low activity of protease (trypsin and aminopeptidase) along the alimentary canal, even though all of the enzymes show no significant difference among the gut sections. The increasing activity of α-amylase from proximal to distal intestine but with a notably drop-off in rectum zone demonstrates its high consumptions on arthropods and plant materials which are available in the environment. Presence of lipase with uniform distribution along the gut is expected due to insectivorous nature of fish, which gives an indication that there is possibility for halfbeaks to assimilate a wider array of diet nutrients. Our findings in this study is thought to be beneficial for improving knowledge on the biology and nutrition physiology of examined species and may provide valuable information on current model of stomachless digestive system, yet further refinement may be necessary.

Abstract: Study on morphometric variations of halfbeak fish (Zenarchopterus buffonis Valenciennes, 1847) from estuary of West Sumatra has been conducted from December 2013 to April 2014. The fish samples were collected from four locations i.e. Batang Tarusan (Pesisir Selatan), Batang Antokan (Agam), Batang Basampan (Padang Pariaman), and Sungai Pisang (Padang). A total of 22 characters of morphometric and 8 characters of meristic were measured and calculated in this study. The data were subjected to the Kruskal Wallis analysis and continued with Mann Whitney test, Principal Component Analysis, and Unweighted Pair Group Method Average Arithmetic. The result showed that 18 characters have high variation. Those characters were Total length (TL), Pre-dorsal Length (PDL), Pre-pelvic Length (PPvL), Length before Anal fin (LBAF), Head depth (HD), Body Depth (BD), Depth of caudal peduncle (DCP), Upper jaw length (UPL), Lower jaw length (LJL), Eye diameter (ED), Length of dorsal fin base (LDFB), Pre-anal Length (PAL), Pre-pelvic Length (PPvL), Length of pectoral fins (LPF), and Length of tail fin (LTF), the number of circular scales on the caudal peduncle (CSCP), the number of branched dorsal fin rays (D), and the number of branched pectoral fin rays (P). Therefore, it was high variation in morphology among halfbeak population in West Sumatra waters. However, there was close morphology appearance between Batang Antokan and Batang Basampan, while Batang Batusan was discrete distantly among other populations.