Well that's pretty vague, so here are some questions:
How long has it been in your tank for?
How big is it?
Is it being bullied by other fish?
What is the tank temp, water conditions, tank size?
Does it show any signs of distress?
If you just got it today or something it could be just stressed from the move, bump up your water temp to mid 80's and use a air pump/airstone to help get more oxygen in the water. Pbass that are small can be sensitive and like clean water conditions, high oxygen, and warm temperatures. My pbass wouldn't eat frozen mysis for the longest time, if you're gonna try frozen go for BLOODWORMS they're irresistable to most FW fish.