Due to its size, Brazil has many aquatic environments such as rivers, lakes and reservoirs. However, siltation, pollution and inadequate exploitation of water resources are becoming increasingly common. This is what has been happening alarmingly to water resources in the Amazon region. In this context, the aim of this study is to characterise the nictemeral variation of some limnological parameters and zooplankton in a tropical igarapé in the northern region of Acre, Brazil. The study area is the Canela Fina stream, located in the rural area of Cruzeiro do Sul - Acre. Through field inspection, the following limnological parameters were measured: temperature (°C), pH, turbidity (UNT), electrical conductivity (¿S.cm¿¹) and dissolved oxygen (%) and total phosphorus (mg.L¿¹) were determined in the laboratory from water samples. A total of 13 samples were taken on a 4-hourly nictemeral cycle. Zooplankton communities are bioindicators of water quality as they are directly influenced by biotic and abiotic conditions and can be very useful in research into the impact of pollutants on communities.