Aspects of the reproductive biology of tetra (Hemigrammus bellottii; Characiformes: Acestrorhampidae) in an area with anthropic activities in Eastern Amazon

Abstract The Amazon biome intense environmental impacts due to the exploitation of natural resources, with aquatic environments being particularly vulnerable to these threats. Hemigrammus bellottii is a fish that inhabits this environment and whose ecology is little know. This study aimed to describe reproductive aspects of H. bellottii in areas impacted by mining and agriculture in the Amazon hydrographic basin and to evaluate the effects of aluminum (Al) and iron (Fe) on its reproductive activity. Collections were carried out in the Capim River basin, southeastern Pará state, Brazil. A total of 195 specimens of H. bellottii (117 females and 78 males) were captured, and the stages of sexual maturation were determined by histological analysis. We evaluated the sex ratio, gonadosomatic index (GSI), allometric condition factor (K), maturation stages, and length at first maturity (L 50 ) during the study. GSI values ​​peaked in January, March, and May for both sexes. The L 50 occurred at 22.07 mm for females and 23.13 mm for males. Only females showed significant variations in the GSI. The predictive effect of environmental variables and metals indicated that aluminum in water and sediment, total dissolved solids, and temperature negatively influenced the GSI of females, while aluminum in water and sediment, iron in sediment, precipitation, and total dissolved solids negatively influenced the GSI of males. Although Al and Fe concentrations were higher, especially in the dry season, the results indicate that such conditions did not influence the reproductive activity of the species, suggesting reproductive plasticity.