So I was doing a water test today, since I still have them in the 10 gallon I have been testing the water about every other day to make sure they don't need a little water change. Anyway I fed them after I did the test and I was watching my big four inch comet go down to the bottom pick up about four of the pea sized gavel and started chewing on them, he spit three of them out almost immediately but then went around the tank with one in his mouth, I could still tell it was in there because the gravel was green. He must have had it in his mouth for about a minute. He was in no signs of distress, didn't look like he was having trouble breathing, he was just swimming around normally "chewing" on the rock. After about a minute he spit it out effortlessly and preceded to pick up another and do the same thing. The other gold fish in the tank will pick up the gravel but they always spit them right out. Should I be worried, this activity seems to keep them entertained. I can't wait to get my 55 gallon tank set up so I can move them out of their tiny tank, maybe they'll stop doing this.