Slightly off-topic, but check out a show called “River Monsters” on Animal Planet when you get a chance.
The guy on this show, professional fisherman Jeremy Wade, travels all over the world to find freshwater horrors that will give you nightmares.
Look for the “Piraya” episode and take a look at the teeth on THAT nightmare.
Or the Wels Catfish, and another called the Goonch. Simply hideous... and gigantic.
THIS is a Piraya,, and that’s Jeremy Wade
http://www.loyolaphoenix.com/im-hooked-river-monsters-captivates-unlikely-viewer
“River Monsters” has been on Netflix streaming. My kids like it.