My wife used to tell me that there were freshwater sharks in Lake Nicaragua, which fronts the town she grew up in. She also said that occasionally there would be a body part or two they'd find washed up on the beach and attribute it to someone that had probably been drinking too much and was frolicking in the water at night! I jokingly would give her some guff about not being any freshwater sharks, but in reality, I figured it could be true!
5-6 years after we were married we traveled to S Florida from AK to do the tourist thing and I believe it was Sea World where they had a tank with some sharks and some information plaques outside the tank, with some information on the freshwater sharks in Lake Nicaragua. It indicated that they were more than likely bull sharks that had swam up the river that flows between Nicaragua and Costa Rica that flows out of the Lake. Of course, she had to rub it in, that what she'd been telling me was true and it took some of the fun away from me jokingly calling BS on her freshwater shark stories!
