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A specimen (125.5 mm in standard length) of bridled jawfish, Opistognathus nigromarginatus Rüppell, 1830 was collected from the Pulau Bidong, Terengganu, Malaysia using research trawler. Opistognathus nigromarginatus previously has been recorded from Southern Africa to the Persian Gulf, India, Thailand, and Vietnam. We document the first record of this species in Malaysia and the southernmost occurrence in the South China Sea and Western Pacific Ocean. Detailed morphometric and meristic data are presented along with brief diagnostic characters.

Climate warming and low pH environment are known to negatively impact all levels of aquatic organism from cellular to organism and population levels. For ammonotelic freshwater species, any abiotic factor fluctuation will cause disturbance to the fish, specifically at the gills which act as a multifunctional organ to support all biological processes. Therefore, this study was designed to investigate the effect of temperature (28 vs. 32 degrees C) and pH (7.0 vs. 5.0) stress on the gill plasticity of Hoven's carp after 20 days of continuous exposure. The results demonstrated that high temperature and low pH caused severe changes on the primary and secondary lamellae as well as the cells within lamellae. An increasing trend of the proportion available for gas exchange was noticed at high temperature in both pH exposures, which resulted from a reduction of the primary lamellae width with elongated and thinner secondary lamellae compared to fishes at ambient temperature. Following exposure to high temperature and acidic pH, Hoven's carp experienced gill modifications including aneurysm, oedema, hypertrophy, curling of secondary lamellae, epithelial lifting, hyperplasia and lamellae fusion. These modifications are indicators of the coping mechanism of Hoven's carp to the changing environment in order to survive.

The growth pattern, diet and reproductive biology of the clownfish Amphiprion ocellaris collected from waters of Pulau Tioman were investigated. The length-weight relationship showed an isometric growth pattern (b = 3) in A. ocellaris. The stomach contents mainly consisted of zooplankton and algae, which showed that the fish is omnivorous and was confirmed by trophic level analysis (2.98 ± 0.29). Fecundity of A. ocellaris ranged from 23-1518 with mean egg count of 582 ± 478, and has positive relationships with body length, body weight, eviscerated weight and ovary weight. The gonads were also described and examined histologically. The ovaries showed 4 stages of maturity, displaying different colours for each stage. The different developments of oocytes were also found in each stage of maturity. The males and non-breeders comprised of both testicular and ovarian tissues. In the males, the testicular tissues were more prominent in the ovotestes, whereas in non-breeders the primary oocytes were more prominent. Absence of testicular tissue in ovaries of females showed that the fish is a protandrous hermaphrodite and sex change may not be reversible. Similar observations have been reported in A. ocellaris of other countries and other Amphiprion species indicating that Amphiprion species show consistency in their reproduction strategy throughout their range. Keywords: Reproductive biology, Growth pattern, Stomach content, Amphiprion ocellaris, Protandrous hermaphrodite

The population genetic diversity and demographic history of the longtail tuna Thunnus tonggol in Malaysian waters was investigated using mitochondrial DNA D-loop and NADH dehydrogenase subunit 5 (ND5). A total of 203 (D-loop) and 208 (ND5) individuals of T. tonggol were sampled from 11 localities around the Malaysian coastal waters. Low genetic differentiation between populations was found, possibly due to the past demographic history, dispersal potential during egg and larval stages, seasonal migration in adults, and lack of geographical barriers. The gene trees, constructed based on the maximum likelihood method, revealed a single panmictic population with unsupported internal clades, indicating an absence of structure among the populations studied. Analysis on population pairwise comparison ФST suggested the absence of limited gene flow among study sites. Taken all together, high haplotype diversity (D-loop = 0.989–1.000; ND5 = 0.848–0.965), coupled with a low level of nucleotide diversity (D-loop = 0.019–0.025; ND5 = 0.0017–0.003), “star-like” haplotype network, and unimodal mismatch distribution, suggests a recent population expansion for populations of T. tonggol in Malaysia. Furthermore, neutrality and goodness of fit tests supported the signature of a relatively recent population expansion during the Pleistocene epoch. To provide additional insight into the phylogeographic pattern of the species within the Indo-Pacific Ocean, we included haplotypes from GenBank and a few samples from Taiwan. Preliminary analyses suggest a more complex genetic demarcation of the species than an explicit Indian Ocean versus Pacific Ocean delineation.

This study describes the parasites and pathological condition of infected organ of the green mussel Perna viridis from Merambong Shoal, Western Johor Straits, Malaysia. Samples were collected randomly in November and December 2013. Histopathology techniques using Masson’s Trichrome staining protocol were performed and the thin sections were observed under light microscope. Result showed that gonad was the most infected organ followed by the digestive tubule, adductor muscle, intestine and mantle tissue. The parasites (apicomplexa) such as spore-like Nematopsis, macrogamont-like coccidian, mature oocyst-like coccidian, unidentified coccidian and protozoan were found in the adductor muscle, gonad and mantle. Meanwhile, the pathological conditions were found in all infected organs except the gill, such as particular melanin deposits in cytoplasm, Rickettsia-like or Chlamydiae organism and bacteria-like inclusions. Haemocytic infiltrations were found in the surrounding connective tissues of all infected organ...

The tropical conch, Laevistrombus canarium (Linnaeus, 1758) and Canarium urceus (Linneaus, 1758) are ecologically and economically important shellfish species in Malaysia and neighboring region. Their populations, however are currently declining and this histopathological study investigates the aspect of parasitism and diseases that may affect their well-being. Conch samples were randomly collected from their natural habitat and histological sections (4–5 µm) of various organs and tissues were examined under light microscope. This was followed by ultrastructure analysis on infected tissues using transmission electron microscope (TEM). Based on the histological analysis, large numbers of gamonts, sporocysts and trophozoites of Apicomplexa-like parasites were observed in the vacuolated cells and pyramidal crypt cells of the digestive tubules, and in the digestive ducts. Furthermore, coccidian and oocysts-like Pseudoklossia sp. stages were also observed in the cells of the kidney. Apart from that, spores with cyst-like structure were observed in the digestive gland and kidney. Although the parasites were present in most of the organs analyzed, there was no obvious symptom, inflammatory response or mortality incurred on both species, which implies the possibility of a non-virulent relationship like commensalisms or mutualism. However, more investigations, including molecular studies, are needed to confirm the parasite identification and dynamics, and to further evaluate the nature of relationship between Apicomplexa parasites and their host.

Morphometnc data of six dominant families of fish larvae were examined to observe the degree of similarity among the six families. The experiment was conducted in the seagrass-mangrove ecosystems of Gelang Patah, Johor Strait, Peninsular Malaysia. Samples of fish larvae were collected by using bongo net through 30 min subsurface tow. The six dominant families (Terapontidae, Gobndae, Sillaginidae, Nemipteridae, Blenniidae and Leiognathidae) were selected for the morphometric analysis using one-way ANOVA by SPSS and PRIMER 5 software for cluster analysis. All the morphometric characters, total length, standard length, body depth, snout length, head length, eye diameter and pre anal length of the six dominant families of the order Perciformes were found to be significantly different (p

Reproductive biology of the introduced sailfin cat fish Pterygoplichthys pardalis in the Langat River of peninsular Malaysia was studied. Fish samples were collected monthly from Langat River during March 2003 - June 2004. The sex ratio observed for P. pardalis was female-biased with 1: 2. Gonadal maturity stage is achieved at 12.5 cm standard length (SL) for males and 13.0 cm SL for females. This species appeared to have continuous spawning that peaked when water levels were high between September and January. Egg sizes were found to reach as large as 3.3 mm in dia in the ovary; suggesting that they spawn in batches. Fecundity varied from 1297 to 18791 numbers per brood, proportional to individual size. Data obtained from this study indicate that the introduced sailfin cat fish has successfully colonised in Langat River in Malaysia.

Several series of trawl surveys were carried out in the waters of Perhentian Islands using commercial trawlers. 16S mitochondrial rRNA gene sequences were used to infer the phylogenetic relationships among nine morphospecies of leiognathids. The results showed that the genus Leiognathus is paraphyletic, whereas Gazza secutor , Photoplagios , Photopectoralis and Nuchequula are monophyletic. The molecular phylogenetic posions of the leiognathids studied were identical with morphological delineation, except for Photoplagios stercorarius . Branch of P. stercorarius was placed between Photoplagios spp. clade and clade of Secutor and Gazza . P. stercorarius was more affiliated to genus Photoplagios morphologically however have slight different features of light organ system compared with others three Photoplagios sp. caught in this study. It is probable that two distinct subclades occur in genus Photoplagios . Leiognathus equulus formed the base of the other leiognathids. Leiognathus splendens and Leiognathus jonesi formed a sister taxa to Photopectoralis species. Gazza formed a sister taxa to Secutor and Nuchequula formed a sister taxa to the group of trifurcation but toth with low bootstrap support. This study has shown that 16S mitochondrial rDNA is a good marker for phylogenetic analysis of the Leiognathidae.

The study was conducted at the Merambong Shoal, Johor Straits, Malaysia. Strombus canarium was the most abundant herbivorous mollusc within the study site, highly prized as seafood and contributes to the economics of the locals. Ontogenetic development of sex characters and sexual maturity were determined via logistic curve analysis, using shell-length and/or lip thickness as predictors. The minimum shell-length at which sex characters appeared was at 30 mm in males and 32 mm in females and both sexes can definitely be determined at more than 41 mm shell-length. The SX50 (probability of individuals can be sexed is 0.5) was at 38.33+0.41 mm for male and at 37.15+0.31 mm for female. The SL„ (length at which the probability of individuals are matured is 0.5) was at 54.14+0.86 mm shell-lengths for males and at 58.51+1.02 nun shell-lengths for females. The LIP„ (lip thickness at which the probability of individuals are matured is 0.5) values on the other hand was about 0.69+0.0003 and 0.80+0.014 mm for males and females respectively. The findings indicate that sexual dimorphisms occurred at very early stage in S. canarium life history

The Boddart's goggle-eyed mudskipper, Boleophthalmus boddarti (Perciformes, Gobiidae) is an amphibious fish, inhabiting brackish waters of estuaries and builds burrows in soft mud along the intertidal zone. In this paper, the complete mitochondrial genome sequence of B. boddarti was firstly determined. The circle genome (16,727 bp) comprises 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 1 control region. The overall base composition of B. boddarti is 29.1% for C, 28.9% for A, 25.9% for T, and 16.0% for G, with a slight A + T bias of 54.8%. The termination-associated sequence, conserved sequence block domains, and a 131-bp tandem repeat were found in the control region. It has the typical vertebrate mitochondrial gene arrangement.

This study describes the apicomplexa as well as other parasites infecting organs/tissues of the hard clam Meretrix meretrix Linnaeus, from Merambong Shoal, Western Johor Straits, Malaysia. Samples were collected randomly by hand picking, in November and December 2013. Histological techniques were performed, stained using Masson's Trichrome protocol and observed under light microscope. The results showed that gonad and gill were the most infected organs followed by digestive gland, intestine and adductor muscle. No pathology condition was observed in the mantle. Histophatological examination showed that the gregarine, Nematopsis, unidentified coccidian and Perkinsus were found in the gill and gonad, and also in the numerous hemocytes. Other pathological conditions such as bacteria-like inclusion and intracellular bacteria were also observed in the same organs. Further investigations are needed particularly on other molluscs present at the study area. Understanding the morphology and pathology of parasites ...

The volutid, Cymbiola nobilis Lightfoot, 1786, is a gastropods molluscs that inhabit deep seas and traditionally harvested by locals for food and hence fetch a high market value. The objective is to study the development of volutid and larval production as an effort to restore depleted natural population of this species. Egg masses used in this study was collected while still underneath spawning females, and embryonic and post-hatching larval development was observed in the laboratory. The larvae were reared in 50 × 100 cm aquarium with 0.22 μm filtered seawater medium at a salinity of 30 ± 1 PSU. Fecundity was estimated at 29 eggs/egg mass (n=10). The juvenile hatching was exactly the same as the adult. Base on this study the morphological features of Cymbiola nobilis can be assigned to eight different development stages beginning from egg described in this paper. The metamorphosis stage were took place in the egg and it is about 7 days before become pre-hatching juvenile. They showed a short period of metamorphic competence and morphological changes also described.