Morphology of Rhyacichthys aspro (Valenciennes 1837) in mandulog river system, Iligan city, Northern Mindanao, Philipines

A freshwater goby species Rhyacichthys aspro of Family Rhyacichthyidae captured at Mandulog River system was described in terms of its morphometric and meristic attributes, sexual dimorphism and body proportionality. Given its rare status in the river, only 18 total specimens were used in this study. The results showed that morphometric and meristic attributes were not significantly different. This may be due to its highly restricted habitat inside rock bottoms and crevices. Male and female exhibited sexual dimorphism, and that, a arent morphological distinction was observed. It has a well-proportioned body structure that in turn, could be related to a successful courtship, mating and spawning. The results of the study suggest that Mandulog River system, as the habitat and food sources of this goby species, did not pose any threat on the morphology of R. aspro, as it did not show any pattern of adaptations with respect to where it is found in the river system. Since this goby was not found at downstream part of the river would mean that it is sensitive to water pollution, as concentrations of pollutants increased. Thus, reduction of water pollutants and regulation of pollutant-generating human-related activities must be undertaken to protect and conserve this pollution-sensitive goby species.