irridecent shark freshwater fish

Question
I just started my freshwater aquarium about 2 weeks ago,and I put in 2 irridecent shark fish. They seem to lay at the bottom of the tank against the glass but on opposite sides of the tank. One of them also buried its head under the gravel - is this normal behavior?

Answer
It sounds like ammonia poisoning.  New tanks need to be cycled to allow beneficial bacteria to form.  I am not sure what size tank you have, but I know id. sharks need about 200g each as adults.  My suggestion is to return them to the store and research cycling, before purchasing more fish.  It's not your fault, I blame the people at your LFS for selling you those fish.
Here's a good article on the cycling process.
http://www.cichlid-forum.com/articles/fishless_cycling.php