tin-foil barb puts rocks in mouth

Question
Hi! I am wondering what my tin-foil barb is doing; he/she puts rocks in his mouth. I notice this after feeding shrimp pellets. Im unsure if this behaviour is only at feeding time.  
thanks

Answer
Hi Andrea,
 Does he spit them out again?  Many fish will take rocks into their mouth, chew them around and spit out the rocks. They are eating the stuff in and around the rocks. We call this behavior substrate-sifting.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>