Coryd55

What qualifies a fish as a freshwater shark?

Just curious and couldn't find the answer so maybe someone here knows

sirdarksol

It's actually a type of catfish, I believe, that just happens to look like a shark. Except for, perhaps, bala sharks, which are a different kind of fish, more minnowish, that are also shaped like sharks.

Oh, and then there's the bull shark, which is capable of living in nearly any quality of water, including horribly dirty, mud-choked freshwater.
Of course, these guys grow way too large for a tank, and probably fall under the US laws on highly dangerous pets like tigers and cobras.