Catalão Lake is an important reproductive area for one ray species.

Two field surveys were conducted in October 2014 and November 2015 (Shibuya & Duncan 2022). A total of 20 Ocellate Freshwater Stingrays (9 females, 11 males) were captured using bottom longlines over muddy substrate, with 10 individuals caught during each sampling year. Body sizes ranged between 25.5–50 cm disc width (DW) for females, and 25–48 cm DW for males. As size-at-maturity for this species is ~25 cm DW, all individuals were considered mature (Last et al. 2016). Bite wounds on the surface of the pectoral fins (i.e., those which could be clearly identified as bites and abrasion marks) were reported for 10 specimens (4 females, 6 males) with a total of 128 wounds for all specimens assessed (Shibuya & Duncan 2022). This high number of bite wounds on the posterior quadrants compared to the anterior quadrants of females supports previous findings that males grasp the females near the cloaca during pre-copulatory behaviour (Chapman et al. 2003; Arnés-Urgellés et al. 2018; McCallister et al. 2020). Males had a large amount of bite wounds, distributed randomly throughout the body, while females had more bite wounds on the posterior region. The higher number of wounds in males is assumed to indicate aggressive interactions among males in competition for females, caused by attempts to prevent other males from mating with the target female (Shibuya & Duncan 2022). The behaviour is likely due to the confinement of the rays in the lake during the low-water period (Shibuya & Duncan 2022). These observations are mostly related to copulatory behaviour, as Ocellate Freshwater Stingrays reproduce in the low-water period (Charvet-Almeida et al. 2005). Furthermore, one of the animals captured in 2014 was a pregnant female with embryos, which supports the importance of this area for reproductive purposes (Shibuya & Duncan 2022).