Invasive introduced fish species are well known for their deleterious impacts on aquatic biodiversity and environment. This study provides the first report on the occurrence of introduced Amazon sailfin catfish, Pterygoplichthys pardalis from the Gombak basin, Selangor, Malaysia, where the suckermouth catfish, Hypostomus plecostomus and vermiculated sailfin catfish, Pterygoplichthys disjunctivus had been previously reported. Besides, selected morphometric and meristic measurements between P. pardalis and P. disjunctivus from the Pusu River, Gombak basin were compared. Moreover, we also described two body patterns of the P. pardalis collected from the river. The body pattern which does not fit entirely with the known characteristics of P. pardalis or P. disjunctivus is suspected to be a result of hybridization between both species, but deeper study should be conducted to confirm this claim.

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This study aimed to determine the lethal concentration (LC50) of Terminalia catappa leaves extract on three cyprinid species; carp (Cyprinus carpio), goldfish (Carassius auratus) and tiger barb (Puntigrus tetrazona) through the acute toxicity test. The leaves of T. catappa were extracted with methanol and prepared in various immersion concentrations (40, 80, 100, 150, 200, 250, 300, and 350 mg/L). These extracts were immersed in the aquarium and left for 24 h before performing the acute toxicity test. The water quality was also analyzed before and after adding the extract immersions into the aquarium. The acute toxicity test conducted for 96 h with 10 fishes of each cyprinid species (4.0-6.0 cm length) in 30 L water capacity aquarium. The mortality of each cyprinid species was recorded at 24 h time interval and LC50 of the extracts throughout 96 hours was determined through the probit analysis application. Specifically, the LC50 of T. catappa leaves extract were 349.89, 338.65 and 318.48 mg/L exhibited for carp, goldfish and tiger barb, respectively. A high concentration range of any plant-based extract has the potential to become toxic to particular fishes. Thus, it is an effort from this study to identify the safety margin of T. catappa leaves extract before its therapeutic values can be further manipulated and elucidated in aquaculture research.

This study explores the potential effects of alien fishes on the native fish community, well-being, and tropic preferences in selected rivers of Klang Valley, Malaysia. Following the Aquatic Species Invasiveness Screening Kit assessment, most of the alien fishes (80%) are invasive. The alien species occurrences correlated positively (p < 0.05) with poor water quality, such as rivers with high ammonia-nitrogen and nitrite, but negatively with phosphate and dissolved oxygen. Anthropogenic characteristics, such as rivers with high pollution levels and ease of accessibility to the fish habitat, are mainly associated positively (p < 0.05) with the occurrences of alien fish species. In general, the results of fish stomach contents analyses and their associated indices, together with stable carbon and nitrogen isotopes, revealed domination by alien fishes or diet overlaps between both alien and native fish species. This finding indicates that alien fishes benefited from the impacts of the anthropogenic activities in their surrounding habitats, while their plasticity in feeding habits might help them to invade, survive, and dominate in the rivers of Klang Valley, Malaysia.

Recent studies have shown that extracted soil has the potential to enhance microalgae growth. An experiment was conducted, and a kinetic model was developed to understand and predict the growth rate of Dunaliella primolecta with consideration of soil extract effects. Dunaliella primolecta was cultured and mixed with extracted soil from the Raja Musa Forest Reserve, Malaysia. At present, no model of microalgal growth associated with the soil extract effect has been developed to predict cell density and growth rate. A mathematical model was derived to describe the growth rate and cell density production of microalgae with soil extract in the cultured microplate. The prediction model of microalgae concentration agrees with the experimental data, with R2 ranging from 0.94 to 0.98. Culturing microalgae with 1% of soil extract concentration yielded a significant increment of growth rate. However, the growth rate remained constant at a higher concentration, suggesting the percentage as an optimal value. Thus, the soil extract acts as a growth enhancer that doubles the growth rate of cultured microalgae. A parametric study was conducted to characterize the light intensity and temperature effect on the growth model concerning soil extract effect.