Abstract The freshwater prawn Macrobrachium jelskii (Miers, 1877) is a species with wide geographical distribution. However, the biological and ecological aspects of this species are poorly studied. Thus, the present study was carried out in Batateiras River, at the municipality of Juazeiro do Norte, located in the south of Ceará, in the semiarid region of northeastern Brazil. Samples were carried out monthly between January and December 2013, along the river margins. A total of 628 M. jelskii specimens were collected, 347 males and 281 females. The overall sex ratio was 1:0.81 (M:F). In relation to the carapace length, males reached sexual maturity at 5.1 mm while females reached morphological sexual maturity at 7.1 mm. Females were morphometrically larger than males, with means of 7.04 mm (± 1.61) and 5.97 mm (± 0.78), respectively. The ovigerous females were more frequent in the rainy season. Female fecundity showed a positive correlation with growth. Thus, our results report previously unknown information about M. jelskii for a semiarid region of northeastern Brazil.