Fish are the predominant group of vertebrates in aquatic environments, and they are directly affected by the presence of contaminants in water bodies, which undergo changes in the structure and function of communities and dynamics of the populations. The aim of the present study was to conduct a systematic review of studies that analyze the reproductive aspects of freshwater teleosts in environments contaminated by pesticides. A systematic search for scientific articles was carried out from 2000 to 2019 using the "Web of Science" database, using the descriptors "fish reproduction", "contamination", "toxicology", "ecotoxicity" and "biomonitoring", combined with the use of boolean operators "AND" and "OR". The content analysis was performed based on the titles and the summary, with a first screening. Then, 98 articles were read in full, with 40 being selected. 24 species of fish were recorded, with a predominance of Danio rerio (17.5%). Insecticides were present in 78% of the studies, mainly Endosulfan (35%) and Cypermethrin (13%). Reproductive endocrine disorders were the most reported pathways of action (57.5%). The effects of pesticides on the reproduction of freshwater teleosts are evident, requiring studies on structural changes in gonads and a decrease in the quality of gametes.

The great biodiversity of neotropical fish species that have external fertilization as a reproductive strategy, like the tambaqui, requires more careful analyzes in toxicological tests of the various pesticides implemented in Brazilian agriculture over the last few years. In this context, the objective of the present work was to evaluate possible sperm alterations in tambaqui (Colossoma macropomum) semen exposed to two different pesticide residues. Seminal samples of sexually mature tambaqui males from a local fish farm were used. Semen was collected eight hours after hormone induction into graduated glass tubes. After initial assessment of the lack of prior activation, the experiment was carried out in a factorial scheme, testing two pesticides widely used in agricultural systems (glyphosate and fenitrothion). For each pesticide, five concentrations were tested (6, 12, 24, 120 and 240 mg/L), with motility analysis at times 0, 30 and 60 seconds after activation. As a control, activation with 0.9% NaCl solution and motility analysis at the same times described for pesticides were used. Results indicate that in natura samples exhibited initial motility of 89.2 ± 4.9% and mean duration of 100 seconds (up to 10% sperm motility). The reduction in sperm motility occurred significantly (p < 0.05) after 30 seconds in all concentrations tested, except for the concentration of 240 mg/L because no activation was observed. The tests described here demonstrate that tambaqui semen was sensitive to the process of exposure to pesticide residues, and can be used in biomonitoring analyzes of the aforementioned agricultural pesticides.