Assessment of Suitability of Kerian River Tributaries Using Length-weight Relationship and Relative Condition Factor of Six Freshwater Fish Species

The length-weight relationship and condition factor of six freshwater fish species were conducted monthly at selected rivers of Kerian River Basin from May 2008 to May 2009. The fish species studied were Devario regina, Labiobarbus sp., Puntius binotatus, Rasbora sumatrana, Acantopsis choironrhycos and Cyclocheilichthys apogon.  The value of fish growth (b) shows that D. regina (b = 3.256), P. binotatus (b = 3.911), R. sumatrana (b = 3.642) and C. apogon (b = 3.623) had positive allometric growth, while Labiobarbus sp. (b = 2.898) and A. choironrhycos (b = 2.427) had negative allometric growth. The mean Kn varied from 1.003 ± 0.109 (A. choirorhynchos) to 1.873 ± 0.203 (R. sumatrana). Of all the fish species, only mean Kn of R. sumatrana showed significant difference among the sampling sites, at P < 0.05, suggesting the fish growth in the Kerian River basin was in a good condition. Keywords: Length-weight relationship, condition factor, freshwater, Kerian River Basin, Malaysi

Population Dynamics of Tinfoil Barb, Barbonymus schwanenfeldii (Bleeker, 1853) in Pedu Reservoir, Kedah

The physico-chemical and biological parameters, species composition and population dynamic of dominant fish species were conducted in Pedu Reservoir in Kedah. The reservoir is considered safe from human activities, although the level of ammonia concentration (3.84 ± 2.65 mg/L) was exceeded the class recommended in Malaysia. 82.94% of fish families were contributed by Cyprinidae, 11.04% of Notopteridae, 3.01% of Bagridae and 2.51% for others. Twenty-four fish species were recorded in the reservoir and were dominated by Barbonymus schwanenfeldii (38.9%), followed by Oxygaster anomalura (12.4%) and Notopterus notopterus (11.0%). The length-weight relationships of B. schwanenfeldii was an isometric (b = 2.992) form with Kn ranging between 0.75 and 1.01. This fish could attain L? = 30.95 cm at growth rate of K = 0.66 yr-1, given the growth performance index (Ø’) of 2.801 that was represented from two cohorts occurred in August and February, respectively. The cohorts were strongly correlated to rainfall distribution in the area. The total mortality coefficient (Z) was 2.01 and natural mortality coefficient (M) was 1.37 yr-1 given the fishing mortality coefficient (F) and exploitation rate (E) was at 0.64 and 0.32 yr-1, respectively. The exploitation rate of 0.32 yr-1 was lower than the 75% of B’/R (E 0.1 = 0.41)  or optimum Y’/R (Emax = 0.53) indicating the yield per recruit of B. schwanenfeldii could be increased slightly by increasing the E. Keywords:  Barbonymus schwanenfeldii, length frequency, population parameters, management, Pedu Reservoir; Keda