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Background The Temengor Reservoir is the second largest reservoir in Peninsular Malaysia. Located in the northwestern state of Perak, it was selected to develop a large-scale tilapia (Oreochromis niloticus) aquaculture facility within the Aquaculture Industrial Zone (AIZ) in 2008 due to its favourable environmental conditions. No record of tilapia has ever been reported in the natural waters prior to this. However, a post-establishment study recorded tilapia sightings in the natural waters of this lake. The cultured tilapia was easily recognizable with the elongated mouth and body, and long caudal fin. It is postulated that these were escapees from the floating cages that had invaded the natural waters and would negatively impact the native fish species. To test our hypothesis, we investigated the impact of the aquaculture facility on native fish diversity through a spatial design. Methods The study was focused on assessing the impact of tilapia culture at sites nearer to the AIZ vs more distant sites, the former with a greater likelihood of receiving escapees. Two major sites were chosen; within 5 km (near-cage) and within 5–15 km (far-cage) radii from the AIZ. Fish sampling was conducted using multiple mesh sizes of gill nets (3.7, 5.1, 6.5, 7.6, and 10.2 cm) deployed at the littoral zone of the sampling points. Species diversity, abundance, dietary habits, and habitat preference were investigated. Results The CPUE (individual/hour) of native fish species at the far-cage site of the AIZ Reservoir was found to be significantly higher (p < 0.05) than that at the near-cage site. Principal component analysis (PCA) based on diet and habitat preferences showed that the tilapia, O. niloticus had almost overlapping diet resources and habitat with native fish species. Conclusion We conclude that there is a correlation between the reduced catches of native species (based on CPUE) and the high presence of tilapia. Thus, appropriate actions must be implemented for strategic and effective planning in terms of native fish conservation.

Background: The Temengor Reservoir is the second largest reservoir in Peninsular Malaysia. Located in the northwestern state of Perak, it was selected to develop a large-scale tilapia (Oreochromis niloticus) aquaculture facility within the Aquaculture Industrial Zone (AIZ) in 2008 due to its favourable environmental conditions. No record of tilapia has ever been reported in the natural waters prior to this. However, a post-establishment study recorded tilapia sightings in the natural waters of this lake. The cultured tilapia was easily recognizable with the elongated mouth and body, and long caudal fin. It is postulated that these were escapees from the floating cages that had invaded the natural waters and would negatively impact the native fish species. To test our hypothesis, we investigated the impact of the aquaculture facility on native fish diversity through a spatial design. Methods: The study was focused on assessing the impact of tilapia culture at sites nearer to the AIZ vs more distant sites, the former with a greater likelihood of receiving escapees. Two major sites were chosen; within 5 km (near-cage) and within 5-15 km (far-cage) radii from the AIZ. Fish sampling was conducted using multiple mesh sizes of gill nets (3.7, 5.1, 6.5, 7.6, and 10.2 cm) deployed at the littoral zone of the sampling points. Species diversity, abundance, dietary habits, and habitat preference were investigated. Results: The CPUE (individual/hour) of native fish species at the far-cage site of the AIZ Reservoir was found to be significantly higher (p < 0.05) than that at the near-cage site. Principal component analysis (PCA) based on diet and habitat preferences showed that the tilapia, O. niloticus had almost overlapping diet resources and habitat with native fish species. Conclusion: We conclude that there is a correlation between the reduced catches of native species (based on CPUE) and the high presence of tilapia. Thus, appropriate actions must be implemented for strategic and effective planning in terms of native fish conservation. [ABSTRACT FROM AUTHOR]

The aquaculture industry is crucial for sustainability and food security. Nevertheless, it is also one of the significant causes of water quality degradation, reducing water bodies' carrying capacity. One of the degradation factors is the improper discharge of phosphorus. This study aimed to evaluate the trophic state index (TSI) and carrying capacity for tilapia aquaculture development at the Temengor Reservoir, Malaysia, based on the Dillon–Rigler phosphorus budget model. The data permit the evaluation of the limit for fish production capacities that could retain acceptable water quality conditions. This study was carried out monthly from April 2014 to March 2015, focusing on cage sites within the Aquaculture Industrial Zone (AIZ). A total of 15 sampling points were established within a 5 km radius of the fish cages at 1 km horizontal intervals. The TSI values based on three indicators, total phosphorous, Secchi depth and chlorophyll‐a, showed a significant difference (p < 0.05) among sampling points. Areas in the vicinity of the fish cages (<3 km) were at a eutrophic state. However, the current aquaculture production at 9.13 × 103 tonnes per year, which comprises three fish cage modules, has not yet reached the optimum capacity of 325.23 × 103 tonnes per year. Although the lake could accommodate another 105 fish cages, the eutrophic state near the cages signalled water quality deterioration. As there is a plan to increase the number of cages, it is hoped that these findings will be taken into serious consideration in the implementation of any aquaculture expansion in this man‐made lake. [Correction added on 13 September 2022, after first online publication: study date range has been updated.] [ABSTRACT FROM AUTHOR]

A preliminary study of fish inventory within Seberang Perai Utara (SPU) and Penang Integrated Agriculture Development Authority (IADA) irrigation canals system was conducted at six different sampling stations by using three sets of cast net from October 2011 to February 2012. In situ water parameters indicated that SPU and IADA irrigation canals are in good and healthy condition that support a lot of aquatic organisms such as fishes. A total of 22 species consisted of 11 families with 942 specimens was captured and identified during the study period. Cyprinidae is the dominant family recorded, which represents 45.6% of the total number of species recorded followed by Bagridae and Osphronemidae (9.2 % each) and another eight fish families with 4.5 % each. The first five dominant species can be found at all sampling stations. The species are Osteochilus hasseltii, which represents 27.3% of the total specimens captured followed by Pristolepis fasciatus (18.6%), Puntius altus (16.0%), Anabas testudineus (13.1%) and Cyclocheilichthys apogon (10.3%). This study also showed that armored catfish (Hypostomus plecostomus) has been widely distributed in Penang IADA irrigation canals that three out of six sampling stations are positive recorded. This inventory study should be extended and continued as the species checklist present here is a preliminary checklist that is yet to cover the entire Penang IADA irrigation canals. [ABSTRACT FROM AUTHOR]

A study on the distribution of freshwater fishes at several lotic systems around Bukit Merah Reservoir, Perak, Peninsular Malaysia has been conducted for 15 months, starting from November 2012 until January 2014. The study areas covered five river feeders, namely Sungai Merah, Sungai Ara, Sungai Kurau, Sungai Jelai and Sungai Jelutong with eight stations that flow into the Bukit Merah Reservoir. Forty two fish species, out from 16 families with 1856 specimens were recorded during the study period. No endemic or protected fish species has been recorded whereas only one exotic fish species, i.e. Barbonymus gonionotus has been recorded at lotic system. Sungai Kurau recorded highest species number with 26 species followed by Sungai Ara (25), Sungai Merah (21), Sungai Jelutung (19) whereas the lowest has been recorded at Sungai Jelai with 16 species. The first three dominant families were Cyprinidae, which represent 38.1% of the total species caught followed by Bagridae (11.9%) and Channidae (9.5%). Cyprinids become the most abundant fishes that represent 38.0% of the total individuals caught followed by Bagridae (12.0%) and Channidae (10.0%). However, this fish species checklist was not completed yet due to limited utilization of sampling gears which use solely on cast net. Hence, further study in terms of fish distributions by using different types of sampling gear should be carried out. [ABSTRACT FROM AUTHOR]