Science Heritage Journal | Galeri Warisan Sains (GWS)

Microplastic pollution is increasingly found in seafood, but there is a lack of baseline data for many Malaysian commercial fish. This preliminary study sought to (i) characterize stomach content composition and (ii) carry out a preliminary visual search for possible microplastics in four popular commercial species of fish sold in Johor, Peninsular Malaysia: Indian mackerel (Rastrelliger kanagurta), herring scad (Alepes vari), donkey croaker (Pennahia anea), and Indian threadfin (Leptomelanosoma indicum). Fresh and unblemished fish were measured (total and standard length), dissected, and stomach contents analyzed under a light microscope (100×-400×) after gentle agitation with distilled water. In general, natural prey consisted mainly of planktonic fractions (e.g., copepods and phytoplankton fragments) with supplementary benthic cues such as polychaetes, crustacean parts, eggs, detritus, and shell fragments, suggesting pelagic-demersal linkages in coastal food webs. Fibrous and other non-cellular particles without overt biological detail were sporadically encountered and recorded as possible microplastics based on morphology (shape, uniformity, and color), but polymer identification was not attempted. In any case, the findings offer a preliminary descriptive baseline for these market fishes and demonstrate the utility of gut content ecological studies in conjunction with preliminary microplastic analysis to inform future quantitative surveys with contamination control, density fractionation, and spectroscopic analysis. These observations are timely because all four species are popular in Malaysian cuisine. Future research should extend coverage, sample size, procedural blanks, particles per fish and per gram, and polymer identification by FTIR spectroscopy.