How to get clown loaches to eat?

I bought 3 fairly small clown loaches at petsmart the other day ago, but they won't eat anything. I try feeding them hikari waffer, hikari bloodworm, tetra flake food, tetra pellet, aquarian shrimp pellet, and still no luck. They just hide a lots and when they come out, they just go to inactive mode. Are they sick are something?