Size growth and age of two congeneric archer fishes (Toxotes jaculatrix pallas, 1767 and Toxotes chatareus Hamilton, 1822) inhabiting Malaysian coastal waters

The size, growth and age of two congeneric archer fishes Toxotes jaculatrix and Toxotes chatareus collected from Johor coastal waters, Malaysia was studied. The standard length (SL) and body weight (BW) ranges of the two species caught in the study area were 7-12.2 cm SL (9.35±0.19 cm), 11-55 g BW (27.04±1.62 g) and 8-12.2 cm SL (9.88±0.17cm), 15.12-54g BW (30.52±1.72 g), respectively. The ratio of male and female specimens of T. jaculatrix and T. chatareus were 70%, 30% and 68.6%, 31.4%, respectively. The estimated von Bertalanffy growth parameters were L∞ = 12.78 cm, 13.59 cm and K = 1.46 year-1, 1.53 year-1 with a growth performance index of Ø’ = 5.48 and 5.64 in both species, respectively. In order to determine the age, the technique of reading and interpretation of the daily growth increments/rings in the sagittae otoliths and scales were applied. Daily growth increments and annulus of scales counts confirmed that the ages of the samples for both species were typically less than one year (<1) and the remnant samples were between one and two years. The similarity between scale and otolith age determination was identical and dissimilarity was observed only in few samples of both species

Habitat preference and usage of Strombus canarium Linnaeus, 1758 (Gastropoda: Strombidae) in Malaysian seagrass beds.

Despite their economic importance, the ecology of Strombus canarium is poorly understood and factors influencing their habitat preferences remain largely unexplained. The species was reported as highly associated with seagrass bed ecosystems, but their distribution and specific preferences within the habitat remain unknown. Determining the mechanisms that regulate conch distribution and abundance is of fundamental importance for management of the species. In this study habitat preference and usage of conch in their natural habitat were investigated. The population was patchily distributed and present in local colonies that comprised of mixed age groups. There was high spatial variation in conch abundance, where multivariate analysis (PCA) showed high preferences for microhabitat with mixed seagrasses dominated by Halophila spp. Other important habitat characteristics preferred were high sediment organic content (% LOI), high sediment sorting (φ), and low mean sediment particulate size. Areas with dense Enhalus acoroides meadows, though in many reports have been linked with the species, were surprisingly the least preferred microhabitat. It is concluded that the preference towards specific microhabitat within the seagrass bed is associated with their feeding, and intra-specific interactions among individuals

Diet composition of cobia fish, Rachycentron canadum (Linnaeus, 1766) from northeastern waters of Peninsular Malaysia

A study was conducted to investigate the food and feeding habits of cobia, Rachycentron canadum from the northeastern waters of Peninsular Malaysia. Stomach content of 82 R. canadum fish were analyzed with reference to gender and size classes. Fish was the most dominant diet component for R. canadum with % IRI value of 95.3%, followed by squid (3.1%), crab (1.5%), and shrimp (0.07%). Fish was also predominant regardless of gender and size classes of the R. canadum in the study area. Shrimp was not taken by the male, but found in females with sizes ranged between 80 and 120 cm TL. Rachycentron canadum that was larger than 120 cm TL also did not prefer crab as part of its diet component. Their feeding intensity increased with size accordingly that was indicated by the increase in the percentage of active feeder. This research finding will contribute to the development of R. canadum culture in Malaysia

Population growth and reproductive potential of five important fishes from the freshwater bodies of Bangladesh

Population growth (length-weight relationship), and reproductive potential (e.g. fecundity, and sex-ratio) of five important fish species (‘mola’: Amblypharyngodon mola, ‘puti’: Puntius sophore, ‘tengra’: Mystus vittatus, ‘shing’: Heteropneustes fossilis and ‘taki’: Channa punctatus) collected from two important fresh water bodies (namely Hilna beel and Beel Kumari beel) Rajshahi, Bangladesh, were studied. Population growth pattern by length-weight relationship (W=aLb ) for the species differed, and exhibited positive allometric growth (P. sophore in Hilna beel), isometric growth (A. mola and C. punctatus in Hilna beel) and negative allometric growth (M. vittatus & H. fossilis in Hilna beel and A. mola, P. sophore, M. vittatus, C. punctatus and H. fossilis in Beel Kumari beel). The results denoted that fecundity of mature females followed a non-linear relationship (F=aLb ) with total length and exhibited positive allometric growth (b>3) with some exception (A. mola in Hilna beel and M. vittatus in Beel Kumari beel). Fecundity of mature females also increased with total body weight and ovary weight following a linear relationship (F=a+bW). Differences in values of sexratios with seasons for all species in this study may have resulted from different environmental factors as well as breeding seasons. The findings of this study would be useful in imposing adequate regulations for the conservation of these fascinating fishes in the fresh water bodies of Bangladesh

ND5 gene marker reveals recent population expansion of wild Pearse’s mudskipper (Periophthalmus novemradiatus Hamilton) inhabits Setiu Wetlands in East Peninsular Malaysia

Genetic variation and differences in wild Pearse’s mudskipper Periophthalmus novemradiatus populations from Setiu Wetlands in East Peninsular Malaysia were analysed using the partial mitochondrial DNA ND5 gene sequences. Among the 91 individuals sampled from six different localities, 35 novel putative haplotypes of P. novemradiatus were detected. 77% (27) of the haplotypes were unique sequences, with high level of haplotype diversity (H = 0.875) and low nucleotide diversity (π = 0.0037), contributing to the overall highly diversified gene pool of the P. novemradiatus. This reflects a large effective population size with current population expansion, which allows the retention of new alleles in populations. However, due to insufficient time, the accumulation of deeper divergent groups among haplotypes was not possible. Hap05 is the most dominant (33%) and widespread haplotype, followed by Hap11 and 31. Low genetic differentiation with high gene flow was detected between sampling sites, and no pattern for isolation by distance was observed despite being territorial creatures. All sites are at the top priority for conservation because they possess unique haplotypes that are only present at the respective location. Further samples collection from other native regions are required to provide full understanding of its genetic distribution and phylogeographical study over larger scale of geographic regions. Heuristic approach to study other species in this area prior to gazetting the Setiu Wetlands as state park is required in order to conserve the biodiversity in-situ

Condition factors of two archerfish species from Johor Coastal Waters, Malaysia

Archerfishes Toxotes chatareus (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767) inhabits mangrove estuaries, which are a critically important habitat as a spawning and nursery ground as well as the full life cycle of many fish species. In order to manage and conserve resilience fish species like the archerfish, we need to know some basic parameters about their biology and life history. Our research has focused on understanding the annual condition factors of these two species of archerfishes, as a complimentary to other several biological aspects of this two species that have been published. Our results indicated that, both species are in good conditions as the mean values of condition factors (Fulton condition factor K and Relative condition factor Kn) are greater than values of unity (K, Kn >1). The average K and Kn values of T. chatareus and T. jaculatrix were lowest in November and highest in September, indicates the spawning and recovery condition of the fishes. Condition factors measure overall fish population health that can be used by fisheries biologists and resource managers in proper management of fish resources in Malaysia waters

Preliminary checklist of marine invertebrate fauna within the intertidal of Teluk Penyabong and Teluk Gorek, Mersing, Johor, Malaysia

Study on the biodiversity and distribution of marine invertebrate fauna within the intertidal areas of Teluk Penyabung and Teluk Gorek, Mersing has been conducted from July 4th to 9th, 2010. Field sampling was carried out using a transect line method, during the low tide period. The transect line was laid down along the tidal height, perpendicularly to the shoreline. All marine invertebrates encountered within 1 m areas of the line were recorded. Species that could not be identified on site were taken and preserved in 5% formalin for further analysis and identification. Results showed that mollusk was the most dominant phyla, followed by the crustaceans and other organisms. Among the mollusks, the Littorinidae, Neritidae, Muricidae and Patellidae was the most common and can be found in all stations. Within the crustaceans the fiddler crab (Ocypodidae) and tree climbing crab (Sesarmidae) was the most common. In areas with hard substrates, the acorn barnacles (Chthamalidae) were also found abundant. In this paper the biodiversity and distributional pattern of marine invertebrate fauna within the intertidal areas of the study sites were documented and discussed

Morfologi struktur halus organ deria-elektro (Ampullae of Lorenzini) ikan yu Carcharhinus melanopterus, C. limbatus dan Chiloscyllium griseum

Satu penyelidikan telah dijalankan untuk mengesan struktur halus organ deria-elektro (Ampullae of Lorenzini) pada Carcharhinus melanopterus, C. limbatus dan Chiloscyllium griseum. Organ ini amat peka terhadap beberapa bentuk rangsangan terutamanya untuk mengesan kedudukan mangsa, penentuan arah dan mengawan. Di dalam makmal, suatu bahagian organ deria ini dipisahkan daripada lapisan dermis kepala ikan yu. Pemerhatian dan pengambilan imej struktur organ deria telah dibuat menggunakan mikroskop elektron imbasan (SEM). Imej-imej yang diperoleh jelas menunjukkan organ deria pada Carcharhinus melanopterus, C. limbatus dan Chiloscyllium griseum berbentuk ampulari terkumpul di dalam kluster. Saluran-saluran deria yang menghubungkan ampula dengan pori didapati mempunyai orientasi panjang dan susunan yang berbeza-beza pada spesies yang berlainan

Fine structure of gills and skins of the amphibious mudskipper, Periophthalmus chrysospilos Bleeker, 1852, and a non-amphibious goby, Favonigobius reichei (Bleeker, 1853)

Background. Periophthalmus chrysospilos and Favonigobius reichei are most abundant gobies species (Family: Gobiidae) inhabiting estuaries in the west coast of Peninsular Malaysia. Thirty-six goby species are amphibious: the rest remain in water, like other teleosts. However, information on the fine structure of gills and skins of these gobies species that may help to understand their functions in air breathing is still lacking. This study was aimed at describing fine structure of the gills and skins of these two co-existing species of gobies living in the terrestrial and aquatic environment. Materials and methods. Fifty-six specimens of amphibious (Periophthalmus chrysospilos) and 67 specimens of nonamphibious gobies (Favonigobius reichei) were collected from estuary. Gills and skins were dissected out and samples were treated following the standard electron microscopy sample preparation. Samples were affixed onto specimen stubs with silver paint and then coated with a thin layer of gold using a BIO-RAD-SC500 ion sputter. All samples were viewed using SEM Series XL 30, Philips. Results. P. chrysospilos possesses short, thick, bent and twisted gill filaments whereas the F. reichei has long, thin, and straight filaments. There were differences in shapes and numbers of the secondary lamellae attached to the filaments in P. chrysospilos and F. reichei. The skin of F. reichei also has a significant difference in architectural build-up compared to P. chrysospilos. The functional adaptation on the use of gills and skins in P. chrysospilos and F. reichei in natural environment are discussed. Conclusion. The gills of P. chrysospilos show some unique features (i.e. low density of secondary lamellae and smaller gill rakers) that can be used to explain the animal′s ability to successfully live out of water in comparison to F. reichei that are more adapted to aquatic life like other teleosts. Special architectural plan of gills and skins of both goby species may have contributed to their existence in the estuary area