Ecological Assessment of the Amazon Sailfin Catfish (Pterygoplichthys Pardalis) In the Langat River, Malaysia
This study identified the ecological characteristics of an exotic fish species, Pterygoplicthys pardalis that have successfully occupied Malaysian rivers. The objectives of the study were to investigate the existing environment of Langat River where this species were found which included the wate...
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| Format: | Thesis |
| Language: | English |
| Published: |
2008
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/5152/1/FS_2008_36%20IR.pdf |
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| Summary: | This study identified the ecological characteristics of an exotic fish species,
Pterygoplicthys pardalis that have successfully occupied Malaysian rivers. The
objectives of the study were to investigate the existing environment of Langat River
where this species were found which included the water quality, food availability
and habitat types, and to understand the basic ecology of the fish species including
feeding, growth, reproduction that have contributed to the successful colonisation.
The prediction was if the existing environment is suitable for the species, then the
survival of the species will be enhanced due to favorable growth and reproduction.
The study was conducted in Langat River between January 2003 and December
2004, and seven sampling sites (S-1 to S-7) were established. Statistical inference
was used to estimate certain parameters (physical and biological) that are important
in hypothesis testing. The physicochemical parameters of the water except
dissolved oxygen (< 5 mg/l), total suspended solid (> 400 mg/l), chemical oxygen
demand (> 50 mg/l) and ammonia-nitrogen (> 0.2 mg/l) were within the tolerance levels to most indigenous fish species. In the existing environment, the P. pardalis
showed a negative allometric growth dimension (b = 2.538 ± 0.039). The influence
of seasonal rainfall (water level) on the condition of P. pardalis was not evident.
Good structure and function of its digestive tract has enabled the consumption of
many and various kinds of food materials. Small size food particles (< 500 μm) were
preferred and detritus from sediment was its major diet composition. The percentage
of the food items identified both in the stomach and on the river bottom was almost
similar, indicating that this fish fed on the food available in the habitat. The
reproductive performance of this species was based on the male-female ratio of 1:1.7
and continuously reproduced that peaked during the rainy season between
September and January. The number of eggs (fecundity) varied from 1,297 to 18,791
per brood and they were asynchronic batch spawner. Eggs were deposited deep
(about 1 m) in the burrow to hide them from predators. Pterygoplichthys pardalis is
a hardy species and exhibited typical characteristics of an invasive species where it
has successfully survived in the Langat River. |
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