Which freshwater lake has sharks?

Lake Nicaragua or Cocibolca or Granada is a freshwater lake in Nicaragua.

Lake Nicaragua, despite being a freshwater lake, has sawfish, tarpon, and sharks. Initially, scientists thought the sharks in the lake belonged to an endemic species, the Lake Nicaragua shark (Carcharhinus nicaraguensis). In 1961, following comparisons of specimens, it was synonymized with the widespread bull shark (C. leucas), a species also known for entering freshwater elsewhere around the world.

It had been presumed that the sharks were trapped within the lake, but this was found to be incorrect in the late 1960s, when it was discovered that they were able to jump along the rapids of the San Juan River (which connects Lake Nicaragua and the Caribbean Sea), almost like salmon. As evidence of these movements, bull sharks tagged inside the lake have later been caught in the open ocean (and vice versa), with some taking as little as 7–11 days to complete the journey.

Numerous other species of fish live in the lake, including at least 16 cichlids that are endemic to the general region (none are strictly endemic to this lake, although Amphilophus labiatus is native only to the Nicaragua and Managua lakes). A non-native cichlid, a tilapia, is used widely in aquaculture within the lake. Owing to the large amount of waste they produce, and the risk of introducing diseases to which the native fish species have no resistance, they are potentially a serious threat to the lake's ecosystem.