<![CDATA[Graphical Abstract Highlight Research Microplastics were detected in the gills and stomach of S. vermiculatus. Microplastic abundance was higher in the gills than in the stomach. Fiber were the most dominant shaped of microplastic in both organs. FTIR analysis confirmed the presence of PE, PES, PP, and HDPE in a selected subset of particles. Abstract Surveys of organ-specific particles in fish can provide baseline observations, yet visual examination and selective chemical identification require different interpretations. This study employed a cross-sectional observational design to investigate microplastic contamination in paired gills and stomachs samples from Siganus vermiculatus landed at the Palopo Fish Landing Port, Indonesia. Fifteen fish were obtained via convenience sampling from a single catch on August 7, 2025. Organ samples underwent KOH digestion and visually identified using a stereo microscope, while 20 selected particles were analyzed using Fourier-transform infrared (FTIR) spectroscopy with a spectral similarity level of ≥70%. Suspected particles were found in the 15 fish, totaling 107 particles: 64 in the gills and 43 in the stomachs, with mean particle counts per fish of 4.27 ± 1.44 and 2.87 ± 0.99, respectively. The mean paired difference was 1.4 particles/Ind (95% confidence interval: 0.42-2.38; paired t-test: t(14) = 3.073, p = 0.0083). Fibers predominated, with the 1-5 mm size class being the most frequently observed. Seven FTIR spectra met the reported matching criteria, allowing for identification as PE (including HDPE), PES and PP. The higher quantities observed in the gills reflect an organ specific pattern within the sampled fish. The use of plastic storage bags, the absence of procedural blanks, selective FTIR analysis, and single-catch sampling limit environmental attribution and population-level inferences. These findings provide a descriptive baseline for future studies that incorporate contamination controls and repeated sampling.]]>
