Ten univalves and fifteen bivalves of mollusks (shellfish) were identified from the coastal, islands, and reefs during the low tide of inter-tidal and sub-tidal areas of the Sagay Marine environment and subjected to microplastic contamination assessment. Transecting and collecting of samples were done using Global Positioning System (GPS). A minimum of 500 grams of the wet weight of shellfish meat and the extraction and packing in containers were done from the sampling stations and directly delivered to Negros Prawn Producers Cooperative Analytical and Diagnostic Laboratory. Sterilization using wet peroxide oxidation (WPO) chemical digestion and optical microscopy were methods used in shellfish microplastic extraction and identification. Of 25 mollusk (shellfish) meats, 7 or 28% were positive for microplastic fiber contamination. Of the 7 microplastic fiber contaminated mollusks (shellfish), 6 or 24% of them were bivalves, namely: tumid venus (Gafrarium pectinatum), ark clam (Anadara antiquata), cultured oysters (Ostreidae), hooded oysters (Saccostrea cucullata), ventricose ark (Arca Ventricosa) and green mussels (Perna viridis) thriving in the inter-tidal and sub-tidal coastal areas of Bulanon; oysters and hooded oysters from Punta Roma, Old Sagay and Tagnipis, Taba-ao proper of Taba-ao and Vito; the 1 or 4% was univalve which was the trapezium horse conch (Pleuroploca trapezium) thriving in the mangrove sediments of the island of Molocaboc Daku. That microplastic fiber came from worn-out clothes. The reefs of the Sagay Marine Environment had zero microplastic contamination. The microplastic contamination index of commercially identified mollusks (shellfish) in the Sagay Marine was 28%. Univalve and majority of bivalves mollusks (shellfish) that thrive in the mangrove sediments and in the brackish water of Sagay Marine Environment were more microplastic contaminated.