Improper disposal of household and industrial waste into water bodies has transformed them into de facto dumping grounds. Plastic debris, weathered on beaches degrades into micro-particles and releases chemical additives that enter the water. Microplastic contamination is documented globally in both marine and freshwater environments, posing a significant threat to aquatic ecosystems. The small size of these particles makes them susceptible to ingestion by low trophic fauna, a trend expected to escalate. Ingestion leads to adverse effects like intestinal blockages, alterations in lipid metabolism, histopathological changes in the intestine, contributing to the extinction of vulnerable species and disrupting ecosystem balance. Notably, microplastics (MPs) can act as carriers for pathogens, potentially causing impaired reproductive activity, decreased immunity, and cancer in various organisms. Studies have identified seven principal sources of MPs, including synthetic textiles (35%) and tire abrasion (28%), highlighting the significant human contribution to this pollution. This review covers various aspects of microplastic pollution, including sources, extraction methods, and its profound impact on ecosystems. Additionally, it explores preventive measures, aiming to guide researchers in selecting techniques and inspiring further investigation into the far-reaching impacts of microplastic pollution, fostering effective solutions for this environmental challenge.

A twelve week feeding experiment was conducted to evaluate the replacement of fishmeal (FM) with poultry by-product meal (PBM) in practical diets for European sea bass, Dicentrarchus labrax with an average initial weight of 0.89 g. Five isocaloric (5.1 kcal lipid g⁻¹) and isonitrogenous (451 g protein kg⁻¹) diets were formulated with PBM replacing FM at levels of 0% (control), 25%, 50%, 75%, and 100%. The experiment was carried out in 30-in. nylon mesh net cages (hapas). At the termination of the trial, growth performance including final body weight, weight gain, specific growth rate, and protein growth rate of diets containing up to 75% PBM were comparable to those of the control group, whereas the diet with 100% PBM resulted in a significantly lower values (p < 0.05). Feed utilization exhibited variation among the treatments (p < 0.05). Whole body composition also showed significant differences across the dietary treatments. Essential amino acid (EAA) contents specifically arginine (Arg), histidine (His), methionine (Met), and threonine (Thr) in the whole body of fish fed diets with up to 50% PBM replacement were not significantly different from those in the control group. Furthermore, the intestinal microvilli length, width and absorption area increased significantly (p < 0.05) with PBM replacement levels up to 50%. Histological analysis of the liver revealed mild vacuolation of hepatocytes in fish fed up to 50% PBM,while pre-pancreatic fatty degeneration of hepatocytes was observed in fish fed diets with 75% and 100% PBM. Therefore, this study demonstrates that PBM can replace up to 50% of FM in the diets of European sea bass without adverse effects on growth performance, body composition, or liver and intestine morphology.

The experimental trial was conducted to assess the appropriate utilization of dietary lysine (Lys) required for Oncorhynchus mykiss fingerlings. Six isonitrogenous (450 g/kg CP) and isoenergetic (20.9 kj 100 g⁻¹ GE) casein–gelatine based diets supplemented with varying concentrations of dietary Lys (14.0, 16.5, 19.0, 21.5, 24.0. and 26.5 g/kg, dry diet) were formulated. For each incremental level, all diets were randomly distributed in triplicate groups of 20 fish (1.79 ± 0.06 g/fish; 5.70 ± 0.42 cm/fish) and were fed in the morning and evening time (08:00 and 17:00 h) at the rate of 5% BW day⁻¹. After the end of the trial, maximum live weight gain (355.21), protein efficiency ratio (1.69 g/kg), better-feed conversion ratio (1.31) and maximum body protein deposition were recorded at 21.50 g/kg increment of Lys in the diet. Highest body protein, lowest moisture and intermediate fat contents were noted in the fish fed 21.50 g/kg of dietary Lys containing diet, while body ash values did not show any significant (p ˃ .05) changes at each increment of Lys in the diets, except at lower increments, where highest ash content was observed. Hepatosomatic index (HSI) value was noted lowest in the fish fed with diets containing 21.50 g/kg Lys level, while haematological variables also exhibit considerable changes with the addition of each Lys inclusion level. Maximum haemoglobin (Hb), haematocrit (Hct) and red blood cell (RBC) count were also noted at 21.50 g/kg Lys fed diet. Significant variations (p < .05) in plasma variables, non-specific immune system, intestinal enzymatic activities and antioxidant status were also observed in the fish fed with varying dietary Lys containing diets. However, cholesterol, triglycerides, amylase, lipase and superoxide dismutase (SOD) did not show any differences with respect to Lys inclusion levels. Our findings suggest that 21.60 g/kg dietary Lys, corresponding to 48.0 g/kg of dietary protein should be incorporated in the diet of rainbow trout for better growth and efficient nutrient conversion of this species, and also for the improvement in fish health. Collectively, this study indicated that an appropriate amount of Lys improve fish growth, haemato-biochemical parameters, immune response and digestive ability, and also up-regulate the antioxidant status.