Photo from sensingtheshift
The African Tigerfish (Hydrocynus goliath) has one of the most horrific aspects, which fresh-water creature can have and also is the largest Tetra, which fact brings to mind the parallel between the house cat and the tiger, which seems oddly fitting in this case. They can grow up to 1.80 m (6 feet). There is something unnatural in their appearance, the teeth are somehow too big and sharp for the rest of the body, also the colour of the teeth is yellowish which looks also abnormal for fish, which would've been a bit more ordinary if it had at least white teeth. And overall it plainly looks like a movie monster.
Source: Sensingtheshift, Wikipedia