There is growing concern about the ingestion and accumulation of microplastics (MPs) in aquatic organisms, as these particles may negatively impact the aquaculture environment and accumulate in farmed products. This study aimed to quantify and categorize MPs found in the gastrointestinal tract (GIT) of GIFT tilapia reared in a recirculating aquaculture system (RAS), fed both commercial diets and the macrophyte Lemna. To evaluate the effect of plastic tank covers, the experiment included nine uncovered and nine covered tanks. Fish were sampled at the beginning and end of a 90-day production cycle, totaling ten individuals — five per treatment. Following biometry, the GIT of each fish was dissected, digested with 35% hydrogen peroxide (H₂O₂) at 60 °C for 48 hours, and filtered using Whatman GF/F filters. MPs were analyzed under a
stereomicroscope coupled with a digital camera and the ImageView software. Particles were categorized by frequency, abundance, shape (fragments, fibers, pellets, films, and spheres), color, and size.
The analyzed fish ranged from 9.4 to 20.8 cm in total length and weighed between 20.2 and 220.3 g. Comparison of total MP abundance between areas revealed no statistically significant difference (t = 0.558, p = 0.59). However, when particle size was considered, a significant difference was observed between areas (Mann Whitney U = 1.98×10⁶, p = 0.046), with larger particles detected in fish from the uncovered tanks. The predominant particle size class was 45–60 µm. Blue was the most frequently observed color, and fragments were the dominant morphological type in both cultivation areas.
These preliminary results suggest that plastic covers had no measurable impact on MPs abundance during the cultivation cycle; however, they may serve as a barrier against the deposition of airborne particles. Other potential sources of MP contamination—such as water, system infrastructure, and commercial feeds—remain a concern. These findings underscore the importance of implementing strategies for the prevention, reduction, reuse, and safe disposal of plastic materials within aquaculture systems