The objective of this study was to determine the relationship between various stream (or Sungai) ecological factors as regards to fish population density. Stream ecological factors such as substrate type, stream order, habitat type and disturbance status were investigated to estimate their influence on fish presence and density. Fishes were sampled using electrofishing method (Electrofisher Model 15-D Honda EX 350 engine). Results showed that substrate type, stream type and disturbance have significant influence on fish density. On the other hand, habitat type did not significantly affect fish density. Highest fish density was recorded at the stream segment with sand/gravel substrate (21.47 individuals/m 3 ) while segments with sand/silt substrate showed the lowest fish density (2.63 individuals/m 3 ). First order stream had the highest fish density (22.53 individu- als/m 3 ) followed by second order stream (5.86 individual / m 3 ) and third order stream (0.88 individual/m 3 ). Undisturbed streams also showed a significantly high fish density (12.17 individual/m 3 ) as compared to disturbed streams. This study showed that fish density in Sungkai Wildlife Reserve area was very dependent on ecosystem characteristics.