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The jewel cichlid Hemichromis bimaculatus is a popular freshwater ornamental fish with high market demand. However, it is aggressive and difficult to be maintained in captivity. Background colours are known to influence fish aggression, but there is still no such information available on H. bimaculatus. This study was conducted to examine the influence of 6 background colours (black, white, blue, yellow, green or red) on the aggression (chasing frequency), survival, weight gain and feed intake of the H. bimaculatus, through a 60‐day culture trial. At the end of this trial, since the total feed intake and fish weight gain (except black) were similar among all treatments, the green was the most recommended background colour for the H. bimaculatus culture as it has the highest fish survival, followed by the white and yellow. Low fish survival was found under the black, red and blue; hence, these background colours were not recommended. In this study, we suspected that different background colours may induce different aggressiveness degree in the H. bimaculatus, and biting may have occurred to cause low fish survival. Also, the blue was speculated to be a stressful background colour to the H. bimaculatus. Nevertheless, further study is necessary to elucidate these hypotheses. [ABSTRACT FROM AUTHOR]

Fringescale sardinella or Tamban Sisik bones have been discovered can be utilized as sunscreen agent in cosmeceuticals. Its flesh is the main ingredient in keropok lekor or fish crackers in Malaysia and the bones contained very high hydroxyapatite (HAp), (Ca10(PO4)6(OH)2) compound which exhibit as UV light absorber. The percentage yields obtained from the hydrothermal extraction consist of 41.2 ± 0.66% (w/w) of HAp which was almost half of the dry weight of 100 g samples. The additional of manganese and ferum, initiated the novel sunscreen materials from hydroxyapatite-Fe and hydroxyapatite-Mn doped (modified bones). The unmodified HAp recorded with SPF 20 and modified HAp-Mn measured with SPF 40. Modified HAp-Fe emulsions were recorded with SPF 50 as the highest SPF value. Therefore, the bones have been characterized using Fourier Transform Infrared Radiation (FTIR) spectroscopy and X-ray diffraction (XRD).The results obtained clearly indicated that the HAp existence in waste of Fringescale sardinella bones with addition of FeCl2 which exhibits high potential as sunscreen compared to manganese and unmodified bones. Thus, the utilization of waste from the fish bones not only produce value-added products from low-cost resources, but also help in reducing pollution to the environment and preserved the global sustainability. [ABSTRACT FROM AUTHOR]

In vivo and in vitro protein digestibility of 0% to 60% soybean meal protein (SBM) substitution from fishmeal protein was conducted for bagrid catfish Mystus nemurus juveniles. Seven experimental diets containing 35% protein and 15% lipid were fed to bagrid catfish to determine the in vivo protein digestibility. In vitro methods were determined using pH stat, pH shift, spectrophotometric assay and sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS-PAGE) with different enzyme mixtures (crude intestinal extract of bagrid catfish, Lazo 1-enzyme, Hsu 3-enzyme, Saterlee 4-enzyme). In vivo and in vitro protein digestibility decreased with increased SBM protein substitution with highest tolerance level of 10% ( in vivo). pH stat and pH drop methods showed the highest degree of hydrolysis (DH) and relative protein digestibility (RPD) using Saterlee 4-enzyme system. However, pH stat method showed highest correlations ( r2 = 0.9263) with the in vivo results using crude intestinal enzyme extract compared to other enzyme systems. The highest correlation of the in vitro methods using crude intestinal enzyme extracts of bagrid catfish was determined using spectrophotometric assay ( r2 = 0.9284) followed by pH stat ( r2 = 0.9263), SDS-PAGE ( r2 = 0.8348) and pH drop ( r2 = 0.6777). All the in vitro methods tested are suitable to rapidly determine protein digestibility for bagrid catfish except for pH drop. [ABSTRACT FROM AUTHOR]

The impact of tidal events on water quality and on the species composition and distribution of phytoplankton at three stations along Merbok river estuary, Malaysia were investigated. Bacillariophyta was the most dominant group, followed by, in decreasing order, Dinophyta, Chlorophyta, Euglenophyta, Cyanophyta and Cryptophyta. Spring tides had higher total cell number and richness but neap tides had higher diversity (except Station 2) and evenness of phytoplankton at all stations. Spring tides also led to higher salinity, conductivity, total suspended solids, nitrate and orthophosphate but lower pH, dissolved oxygen, transparency, chlorophyll-a and nitrite. No significant effects of tidal changes were observed on temperature, light intensity and ammonia. Oscillatoria spp. was dominant at Station 1, while Cylindrotheca spp. and Cyclotella spp. occurred at all stations and were dominant at Stations 2 and 3, respectively. Higher abundance of phytoplankton at Station 1 corresponded to significantly higher nitrate and ammonia but lower temperature, pH, dissolved oxygen, salinity, conductivity, transparency, total suspended solids, nitrite and orthophosphate. Water quality varied according to the tidal events, which subsequently affected the composition and distribution of phytoplankton, thus reflecting the importance of biotic and abiotic parameters in understanding the overall ecological status of the Merbok river estuary. [ABSTRACT FROM AUTHOR]

Manipulation of stocking densities (10, 20, 30, 40 and 50 larvae L−1), each with or without the presence of shelter was conducted to determine the effects on survival, cannibalism and growth performances of larval bagrid catfish Mystus nemurus (Valenciennes 1840) from 2 to 14 days after hatching. This study revealed that stocking density significantly affected survival, cannibalism, total length, feed intake, specific growth rate and final weight of bagrid catfish larvae. Significantly higher survival was observed at moderate stocking density of more than 20 but less than 50 larvae L−1. Survival was significantly low beyond this threshold and was the lowest at 10 larvae L−1, coincides with the highest cannibalism. Total length, feed intake, specific growth rate and final weight were significantly higher at 10 larvae L−1. Shelter significantly improved total length and feed intake. No significant effects of stocking density and shelter were observed on the apparent feed conversion ratio and coefficient of variation. There was also no significant interaction between stocking density and shelter in all parameters. This study suggests that bagrid catfish larvae could be cultured at more than 20 but less than 50 larvae L−1 with the availability of shelter for optimal larviculture condition. [ABSTRACT FROM AUTHOR]

Manipulation of photoperiod: 24 h light (24L), 12 h light:12 h dark (12L:12D) and 24 h dark (24D); and feeding schedules: day and night feeding (DNF), day feeding (DF) and night feeding (NF) was conducted to determine effects on survival, cannibalism and growth of larval bagrid catfish Mystus nemurus 2-14 days after hatching ( dAH). Photoperiod insignificantly affected all parameters. Feeding schedule significantly affected survival and total length at 6 ( P < 0.049; P < 0.009), 10 ( P < 0.033; P < 0.000) and 14 dAH ( P < 0.013; P < 0.000), respectively, but affected cannibalism at 10 ( P < 0.043) and 14 dAH ( P < 0.013). Survival for DNF was significantly higher than DF. Cannibalism for DNF was significantly lower than NF at 10 and 14 dAH. Total length for DNF was significantly higher than DF and NF at 10 and 14 dAH. At 14 dAH, feeding schedule significantly affected feed intake, final weight and coefficient of variation. For feed intake and final weight, DNF was significantly higher than DF and NF. For coefficient of variation, NF was significantly higher than DF. This study suggests that larval bagrid catfish can be reared at 24L, 12L:12D or 24D but should be fed day and night for improved growth, survival and reduced cannibalism. [ABSTRACT FROM AUTHOR]

The artificially reared bagrid catfishMystus nemuruswas observed for the histological development of the pineal organ and retina and photoresponse in a test tank at hatching to 14?d after hatching. The pineal organ was functional at hatching, and the lens-like tissue was partly ossified forming a pineal window at 6?d. The retina became morphologically functional when the outer segments of single cones were formed, and the eyes were innervated with the optic tectum at 18?h and rods were formed at 36?h. Long and thin single cones were not observed. The larvae exhibited undirected kinetic movement at hatching to 12?h and directed tactic swimming away from a torch after 18?h in response to a torch light. The photoresponse of the larvae was negative at hatching to 30?h and at 6?d to the end of the observation at 14?d, but neutral during a period at 36?h to 5?d. It was evident that the kinetic movement was mediated by light perception with the pineal organ, which was not capable of detecting directed signal information, and that the larvae were capable of directed tactic movement only when vision was involved. The vigorous negative phototaxis at 6–14?d was attributed to the improvement of photosensitivity of the retina and the pineal organ. [ABSTRACT FROM PUBLISHER]

The optimal level of Cosmos caudatus supplementation in fish formulation was conducted by using Mystus nemurus fingerlings in two initial sizes (3.05±0.39 g and 4.45±0.71 g). For Experiment 1, crude leaves incorporated were 0.00, 0.50, 1.50, and 2.00% with 60 days of feeding trial. For Experiment 2, the level of leave extract was 0.00, 0.01, 0.05, 0.10 and 0.20% with an experimental duration of 90 days. Both experiments showed significant differences (P<0.05) for growth performance and condition factor. The highest weight gain for Experiments 1 and 2 were 13.28±3.07 g and 18.51±4.21 g, respectively. There were no significant differences in the whole body content and survival rate for both experiments (P>0.05). The protein level was in the range of 15.70±0.79 to 16.74±1.90% (Experiment 1) and 14.96±1.90 to 15.67±0.55% (Experiment 2). The optimal level of crude leaves and extracts was considered at 0.50% and 0.05%, respectively, for M. nemurus fingerlings. [ABSTRACT FROM AUTHOR]