Kribensis is not eating anything, except my plants

[collegelife101]

I got a 3" male krib two days ago. He is in a 50 gal with 2 med sized senegalus polypterus, 1 med sized ctenopoma and 1 smaller african butterfly fish.
I feed them Hikari dried blood worms and these slow sinking cichlid crumbles. All the fish love these foods except for the krib. He chews on my java ferns, anacharis and whatever other plants he can find. He also likes to grab a mouthful of gravel and spit it back out after chewing it for a second or two. He will not go after the blood worms unless they are right in his face and he won't touch the crumbles even if they pass by him. He spends all his time on the bottom of the tank which has 2 cave areas on either side. None of the fish bother any of the others but the krib is looking thin in the stomach and I'm worried hes not going to get the nutrition he needs from gravel and anacharis... oh and i would prefer to keep my java fern.
Any suggestions?

 

[Algenco]

Kribs will stay close to the bottom. Mine would eat anything that came close. You only have 1? They can get fairly aggressive when paired

 

[collegelife101]

I picked up some plankton. It took a few bites for him to not spit it out, but now he loves it and feeds from the surface for other things. I guess it was a break-in period. He had to get used to non-LFS food.

 

[Radioheadx14]

i think i have a smaller pair, i cant tell because one looks like a male and is super colorful and the other looks female, but i am not sure... And they are only about 1.5" long. Mine eat just like my rainbows... very fast, and eat flakes & frozen food. I see them peck around at algae but never at my plants.

Mine always grab mysis shrimp that are way to big and the constantly bite it, spit it out, bite again, spit out again... over and over until they can swallow them.