Streptococcosis in tilapia (Oreochromis niloticus): a review

Tilapia (Oreochromis niloticus) is a hardy, most cultured freshwater fish in the world. It has been contributing to the world aquaculture since the ancient Egyptian days and remains a major freshwater fish species to be cultured. Although tilapias are more resistant to unfavourable water quality than other freshwater fish, tilapias have been reported to succumb to infection by Streptococcus, which was first observed among the populations of rainbow trout (Oncorhynchus mykiss) farmed in the Shizouka Prefecture in Japan in April 1957. Since then, the disease that is also known as ‘pop eye’ has been reported in many other fish species throughout the world, contributing to an annual loss of approximately USD 150 million. Affected tilapia shows loss of appetite, spine displacement, haemorrhages in the eye, corneal opacity, haemorrhages at the base of the fins and in the opercula. The most prominent signs are uni- or bi-lateral exophthalmia (also known as “pop-eye”), distended abdomen and erratic swimming. Control is mainly through implementing some preventive measure and antibiotic therapy, while vaccination is generally not effective in preventing Streptococcus outbreaks in tilapias

Gonadal histology of tiny scale barb, Thynnichthys thynnoides Bleeker 1852, during mass migration season in Rui River, Perak

This study was conducted to evaluate the gonadal histology of tiny scale barb or locally known as “ikan loma”, Thynnichthys thynnoides Bleeker 1852, during the mass migration season in Rui River, Gerik, Perak. A total of 62 (46 males: 16 females) and 60 (44 males: 16 females) fish were randomly collected along the Rui River in Kampung Kuala Rui (downstream of Rui River) and Kampung Kerunai (midstream of Rui River), from October to December 2013. The collected fish gonads were separated, fixed in 10% formalin and processed for H&E staining. The results showed that female samples collected at Kampung Kuala Rui and Kampung Kerunai was at the stage of ripe and running period which indicated by higher percentage of vitellogenic oocytes compared to other stages of oocytes. Gonads collected from Kampung Kuala Rui demonstrated only massive number of vitellogenic oocytes than other type of oocytes with no presence of atretic oocytes, while all samples from Kampung Kerunai showed the presence of atretic oocytes with the mean at 9±3% from overall oocytes counted, indicating that the fish already released their eggs. The atretic oocytes are characterised by thick ovarian wall, non-oval, shrank and wrinkled shape with less yolk granules in the oviplasm. For male gonads, 100% of samples taken from Kampung Kuala Rui demonstrated ripe and spawning stage which indicated by compacted spermatozoa in seminiferous tubules. However, at Kampung Kerunai, 57% of the samples showed ripe and spawning stage while the other 43% demonstrated spent stage or post spawning characteristics which indicated by flaccid with hollow appearance of seminiferous tubules with little amount of spermatozoa in the tubules. As a conclusion, the results revealed that T. thynnoides migrated from Perak River into Rui River in order to spawn in the area between Kampung Kuala Rui and Kampung Kerunai

A review of the ichthyofauna of Malaysian peat swamp forest

A review of literature showed that numerous intensive surveys have been carried out on the ichthyofauna of the peat swamp forests (PSFs) of Malaysia. This review aims to provide a checklist of blackwater fish species in Malaysia from available published literature, and address their economical importance, conservation status and problems of PSFs. A total of 198 peat swamp fish species from 32 families have been recorded in Malaysia. From this number, a total of 114 species from 23 families, representing about 40% of the known fish fauna in Peninsular Malaysia, were recorded from north Selangor PSF. Meanwhile, a total of 49 species belonging to 18 families, 13 species from seven families, 58 species belonging to 19 families, and nine species from five families were recorded from the peat swamps of Perak, Johor, Pahang and East Peninsular Malaysia (parts of Pahang and Terengganu), respectively. Meanwhile, 31 species from 12 families and 40 species belonging to 13 families were recorded from Sabah and Sarawak, respectively. Family Cyprinidae has the highest recorded species, followed by Osphronemidae, Bagridae and Siluridae. The IUCN Red List revealed 12 threatened species facing risk of extinction. The importance of conserving PSFs was outlined and suggestions made in line with the objectives of conservation. Findings from literature revealed that Malaysia's PSFs are rich in fish diversity, contrary to previous belief, and should therefore be conserved and protected to ensure the richness of their fish diversity

Mesocosm study of microalgae in different weather conditions

Microalgae have valuable contributions in carbon dioxide sequestration. There are no much investigations about motivation of mix microalgae productivity in outdoor cultures. This study aims to evaluate microalgae biomass production in outdoor mesocosms under different weather conditions. The experiment was done in Tilapia pond in the hatchery of fisheries of Universiti Putra Malaysia. Weather parameters were recorded daily. Microalgae seeds were obtained from Tilapia pond effluent and added to eight floating aerated mesocosms. Mesocosms were divided into four treatments. Two g triple supper phosphate: 20g Urea were used as fertilizers. Physical and chemical conditions, microalgae primary productivity and biomass, and species composition were measured every two days. Three cycles were categorized as mix, wet and dry cycles based on weather recording scores. Water quality parameters in Treatments and controls cultures showed significant variations. Primary production variables were higher in the fertilized non-sheltered mesocosms (treatment 1). Productivity variables were lower in the dry cycle and higher in the mix cycle. The highest value of fixed CO2 was (3.2) mg/L/d in treatment 1 in the mix cycle, while the lowest value was (0.11) mg/L/d in treatment 3 and control 1 in dry cycle. Changes in weather patterns are seen in the light and temperature values. Microalgae biomass was lower in dry weather conditions because of effect of high air temperature. Weather conditions and different treatments significantly influenced microalgae species composition, due to the sensitivity in some of them to different light intensities. Chlorophytes were the most abundant due to their ability to adapt with different culture conditions

Water quality, primary productivity and carbon capture potential of microalgae in two urban manmade lakes, Selangor, Malaysia

The impact of climate change and weather conditions in small urban manmade lake is less understood. Most studies are done bimonthly or monthly without reference to weather conditions. The contribution of these small manmade lakes to carbon sequestration was largely ignored. There is not much study about water quality and primary production in relation to weather conditions and weekly observations in tropical lakes. Therefore, this study investigates the potential of using microalgae in freshwater bodies to mitigate global warming through carbon dioxide fixation in urban small manmade lakes. A comparative study for water quality and primary productivity in two manmade lakes was done from September 2014 to July 2015. Weekly sampling in triplicate for 500 ml water samples were done for phytoplankton biomass analysis, alkalinity and nutrient analysis, from the surface of the lake at 0.5m depth. Three sets of 4 BOD bottles were used to measure biological oxygen demand and primary productivity. Physical parameters were measured from surface water by Yellow Spring Instrument multi parameter probe model (YSI-556 MPS ). Water transparency was measured by Secchi disk a nd rain rainfall using rain gauge. Daily recording of weather was done at three times a day, then the weather was classified into three weather conditions. Statistical analyses were done by one-way ANOVA, and principal component analysis (PCA). The average water qualit y parameters of the lake during all weather conditions were : water temperature (28.95 ̊C) & (29.43 ̊C), pH(7.14) & (7.11), electrical conductivity (0.15 mScmˉ¹) & (0.41 mScm ˉ¹), dissolved oxygen (5.5 mg Lˉ1) & (4.5 mg Lˉ1), alkalinity (43.8 mgCaCo3/L) & (148.2 mgCaCo3/L), rthophosphates (0.02mg L’/) & (0.42 mg Lˉ1), nitrate-itrogen (0.20 mg Lˉ1) & (0.07 mg Lˉ1), ammonium- nitrogen ( 0.06 mg Lˉ1) & (0.96 mg Lˉ1), trophic status index (20.6) & (37.5) in Engineering lake and Seri Serdang Lake respectively. High averages of chlorophyll -a concentration were (0.71± 0.10 μ g Lˉ¹) & (3.47 ± 0.96 μ g Lˉ¹) during dry weather conditions in Engineering lake and Seri Serdang Lake respectively. Temporal fluctuations of primary production occurred in Engineering lake and Seri Serdang Lake with average of (0.57± 0.09 mg C Lˉ¹ hˉ¹) & (2.86 ± 0.37 mg C L ˉ¹ hˉ¹) respectively. A principal component analysis extracted two components after Varimax rotation and they contributed (22.50 % &15.56 %) and (28.95% &18.14%) in Engineering lake and Seri Serdang lake respectively. The we ather conditions such cloud covers and rain fall that significantly influence light intensity and water quality which in turn influence primary productivity in both lakes. Water quality, primary productivity and carbon capture potential of microalgae in two urban manmade lakes, Selangor, Malaysia

Preliminary study of selected heavy metal contamination in surface sediment of Merambong shoal seagrass bed

Surface area of Merambong Shoal Seagrass Bed (MSSB) is an important area for aquatic organisms as well as human communities for fishing activity. Present study was conducted to evaluate the current status of selected heavy metals contamination in surface sediments collected from the MSSB. Samples of surface sediments were collected from multiple locations along MSSB. The heavy metal concentrations of the present study were compared with previously conducted studies in similar location, as well as other location in Malaysia. Geofractionation of heavy metals were also determined. Based on the obtained mean concentration of each metal, a few indices were used to demonstrate the present level of contamination in the surface sediment of MSSB. The findings of this research are important for monitoring heavy metals pollution and conservation management

Water quality influences on fish occurrences in Sungai Pahang, Maran district, Pahang, Malaysia

This study assesses the influence of water quality on fish occurrences in Sungai Pahang, Maran District, Pahang, Malaysia. Water quality and fish samplings were conducted at seven sampling sites in the district for 13 consecutive months. We used canonical correspondence analyses (CCA) to determine the influence of water quality on monthly fish species occurrences. The ranges of water quality parameters were quite high considering the measurements were made during rainy and dry seasons throughout the year. A total of 2,075 individual fish was captured which comprised of 22 different families and 65 species. Family Cyprinidae recorded the highest number of fish species of the area (27 species; 41.5%), followed by Bagridae (five species; 7.69%) and Pangasiidae (five species; 7.69%). Three fish species categorized as endangered, including Balantiocheilos melanopterus, Probarbus jullieni and Pangasianodon hypophthalmus were also collected. The collected fish species were divided into three groups (A to C), which was clearly separated in the CCA ordination diagram. The most important water quality variables for the fish occurrences in this river were pH, followed by temperature, conductivity, alkalinity and phosphate. Data analysis indicates that the occurrence of fishes were influenced by a combination of water quality parameters, but not associated with sampling month. The results present a new data from a study of fish assemblage and their habitat condition which may be important in fisheries activity and fish conservation of the river in the future

Fatty acid profile of Chlorella vulgaris commercial cultured in different concentration of fertilizer and salinity

Chlorella vulgaris could be consumed as a complete supplementary food in the diet. Chlorella sp. is high in fatty content, especially Essential Fatty Acid (EFA). Chlorella vulgaris was cultured in different culture media, and then FAME were extracted from the sample following Ostrowski and Divakaran method to the study the fatty acid profile. The result showed the polyunsaturated fatty acid reached to the highest percentage on the seventh day of the cultivation. The cell growth as well as the dry weight reached the peak dung the same day. By looking at the PUFA content in different medium, the modified Bold Basal medium has the highest PUFA content among all. The result also showed that the raw of omega-3: omega-6 is about 2:10. This showed that Chlorella vulgaris could be taken as a balance food

Water quality influences on fish occurrences in Sungai Pahang, Maran District, Pahang, Malaysia

This study assesses the influence of water quality on fish occurrences in Sungai Pahang, Maran District, Pahang, Malaysia. Water quality and fish samplings were conducted at seven sampling sites in the district for 13 consecutive months. We used canonical correspondence analyses (CCA) to determine the influence of water quality on monthly fish species occurrences. The ranges of water quality parameters were quite high considering the measurements were made during rainy and dry seasons throughout the year. A total of 2,075 individual fish was captured which comprised of 22 different families and 65 species. Family Cyprinidae recorded the highest number of fish species of the area (27 species; 41.5%), followed by Bagridae (five species; 7.69%) and Pangasiidae (five species; 7.69%). Three fish species categorized as endangered, including Balantiocheilos melanopterus, Probarbus jullieni and Pangasianodon hypophthalmus were also collected. The collected fish species were divided into three groups (A to C), which was clearly separated in the CCA ordination diagram. The most important water quality variables for the fish occurrences in this river were pH, followed by temperature, conductivity, alkalinity and phosphate. Data analysis indicates that the occurrence of fishes were influenced by a combination of water quality parameters, but not associated with sampling month. The results present a new data from a study of fish assemblage and their habitat condition which may be important in fisheries activity and fish conservation of the river in the future

A review of length-weight relationships of freshwater fishes in Malaysia

This manuscript reviews the length-weight relationships (LWRs) of freshwater fishes in Malaysia. A total of 102 LWRs of fishes gathered from literature pertaining to 64 freshwater fish species were analysed. A meta-analysis from 13 previous reports showed that the b values was ranged from 2.19 (Clarias batrachus) to 4.106 (Barbodes binotatus). Out of 64 observed species, 47 species (11 families) experienced positive allometric growth, while another 23 species (eight families) and 31 species (12 families) were recorded under isometric and negative allometric growth, respectively. The fish LWRs observed can be used as an indicator of environmental changes and fish ecological health for freshwater fishes in Malaysia