If you can see it's jaws the teeth should be quite large and in a 2 opposite V's, they need wood, and vegetables (carrot, sweet potato, courgette etc.) and you never see them during the day.
Easy to keep, and you might not see him at all during day time, just remember that it eats wood and some greens. Too much protein and it will die. It really likes meaty foods, but too much and he gets his stomach all swollen.
You should get some caves, and coco shells, so that it can hide.
The fish poos a lot, and it doesn't really clean the tank, but it looks nice when you catch sight of him..