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 α-
amylase 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.
