Abstract
Lake Mainit, shared by the provinces of Surigao del Norte and Agusan del Norte, represents a critical natural resource with high ecological significance. Tank Goby, locally known as Pijanga, is a native and economically important fish species in the lake. This study aimed to determine the concentrations of heavy metals in the muscle tissue of Glossogobius giuris. A total of nine adult specimens were collected, with body weights ranging from (72–100g) and total lengths from (18–21cm). Homogenized, skinless muscle tissues were analyzed following the standard protocols of the Official Methods of Analysis of AOAC International (21st edition) using modified Silver Diethyldithiocarbamate (SDDC) colorimetric method for Arsenic and Atomic Absorption Spectrophotometry for the rest of the metals. Results showed that the pattern of metal concentrations was as follows: Pb > Ni > Cr > As > Cd across the three sampling areas. Further, no statistically significant differences (P > 0.05) among Barangay Roxas, Canaway and San Pablo for most metals. The findings revealed that all detected heavy metals were below the permissible threshold limits, indicating that samples collected from the three barangays were within acceptable safety standards. These results suggest minimal contamination and indicate that the aquatic environment in the study areas remains relatively safe from excessive heavy metal accumulation. However, previous studies have reported heavy metal concentrations in this species that exceed permissible limits. Therefore, further investigation of other economically important fish species in the area, along with regular monitoring, is recommended to ensure continued food safety.
Keywords: Caraga, Freshwater, Limnology, Muscles, Staple Food, Tank Goby.