I just bought a clown knife fish that is about 4-5 inches long. I put a few feeder guppies and ghost shrimp in his tank and a peice of pvc for him to hide in during the day time anything else u would recommend?

is it just gravel and pvc? i would put other plants in too, or else he most likely will just hide all the time.

Yah there are other assorted plants, rocks, driftwood in there with him.

Is he large enough to eat the feeder guppies and ghost shrimp and how often should i feed him?

i would feed him twice a day like any other normal fish but i would vary his diet. S/he can't eat the smae thing over and over again. Also how big of a tank do you have it in??? they get big meaning you need a BIG tank for it.
Yes i would say he is big enough for all of those.

I have a clown knife, he is a year old and about 20 inches long, I have had him since he was about 3 inches long, he has never eaten anything but feeders, in fact he WILL not eat anything but feeders, i've tried everything from beef hearts, chicken hearts, raw shrimp, brine , california black worms , you name it... he WILL not, and he is now in a 300 gallon tank, very happy very , very healthy... So I don't know or understand why they say not to feed clown knifes only feeders. he is now porkin down about 12 of the largest ones they sell ....... daily!!!!!

there's a blog on our site where the girl has a few clownfish, there's a specific list there of animals, chemical and technical specifications... as of last post, most everything was alive and kicking...

Fishfool @ The Reef Tank