‘Microplastics’ that are tiny plastic granules commonly used in cosmetics and air-blasting and small plastic fragments derived from the breakdown of macroplastics are of serious environmental concern Derraik, 2002; Ryan et al., 2009 and Thompson et al., 2004). In 1970s small plastic fragments was first highlighted in open ocean (Carpenter and Smith, 1972) and these drew attention to the scientific interest on microplastics over the last few decades which unveiled that the expansive and frequent distribution within the marine environment cause potential harm to biological compounds (Rands et al., 2010 and Sutherland et al., 2010) . Plastic trash accumulation in the water habitats is among the most prevalent and lengthy alterations on the planet as a result of widespread usage of plastic in daily life. Microplastics are man-made pollutants that build up in marine and freshwater ecosystems across the world.
Plastic particles move throughout aquatic systems and float, sink or settle depending on the properties of particles (density, shape etc), environmental features (water density, salinity, flow rate etc.) and also water currents and storm events (Bondelind et al., 2020 and Li, Zhang, et al., 2020). Freshwater wetlands are the principal destination of many plastic wastes transported in the watershed as wetlands are often situated in lowlands and low-height landscapes. Plastic that is dumped inappropriately is carried to aquatic systems by pluvial flows (Faure et al., 2015).
There are two types of microplastics named primary and secondary microplastics. Primary microplastics are those that are used in facial-cleansers and cosmetics (Zitko and Hanlon, 1991), or as air-blasting media (Gregory, 1996). Secondary microplastics are derived from the breakdown of larger plastic debris on sea and land (Ryan et al., 2009 and Thompson et al., 2004).
Microplastics have adverse effects on aquatic organisms hampering their ability to ingest prey because of the obstruction of digestive tract (Cole et al., 2013). These also reduce the swimming velocity which affects resistance time of fish when swimming against water flow (Barboza et al., 2020).
The chemical composition of microplastics were identified by FTIR or RAMAN in certain freshwater fish species show differences depending on the species and sampling place, being the polypropylene (Slootmaekers et al., 2019; Collard et al., 2018) and the polyethylene (PE)was reported more frequently (Horton et al., 2018; Biginagwa et al., 2016; Andrade et al., 2019). Other polymers that are found less frequently as Polythylene terephthalate (PET); the ethylenevinyl acetate copolymer (EVA) ; acrylic fibers and polyesters (Collard et al., 2018; Slootmaekers et al., 2019; McGoran et al., 2017 and Bessa et al., 2018).
.In comparison to the concussion created by the microplastic and its growing threat, Bangladesh has very few studies in this area. Hossain et. al. (2019) reported that Pink Bombay-duck, white Bombay-duck, and gold-stripe sardine were obtained from the Northern Bay of Bengal in Bangladesh and microplastics were identified.
The incidence of microplastics in the gastrointestinal tracts of 45 individuals belonging to seven widely found Bangladeshi freshwater fish species with various eating habits is investigated in a study (Khan and Setu, 2022). Davidson and Dudas (2016) first studied the amount of microplastics found in wild and cultured Manila clams (Venerupis philippinarum). Microplastic concentrations in farmed and wild clams did not differ significantly according to them. Birnstiel et. al. (2019) also investigated the amounts of microplastic in wild and farmed mussels (Perna perna). They also analyzed the effectiveness of depuration in decreasing microplastics in wild and farmed mussels. Garcia et. al. (2020) recorded the the presence of microplastics in diferent fish tissue freshwater environment from both farmed and wild sources. Further vast study is required in this field and it needs to be addressed.
Microplastics have been found in a wide range of organisms, including fish, turtles, aquatic birds (Lavers et al., 2019), and mammals (Zantis et al., 2021). Blockage of the gastro intestinal tract, developmental delay, fertility problems, and feeding disruption are all obvious effects of microplastic ingestion by aquatic species (Cole et al., 2015; Nelms et al., 2018; Sussarellu et al., 2016). Damaged DNA, cirrhosis, oxidative pressure, embryo toxicity, lipid peroxidation, and defective riposte have all been linked to plastics accumulated in fish (Brandts et al., 2018).
Hossain et. al. (2019) reported that Pink Bombay-duck (Harpodon nehereus), white Bombay-duck (H. translucens), and gold-stripe sardine (Sardinella gibbosa) were obtained from the Northern Bay of Bengal in Bangladesh and microplastics were identified. Microplastics were studied in the gastrointestinal tracts of fish using an alkali digestion regimen, microscopic views, and chemical analysis using a micro-Fourier Transformed Infrared Spectroscope (-FTIR).
The target of this study is to identify the presence of MPs in the gastrointestinal tract (GIT) of cultured and wild freshwater fish.