belly rubbing

Question
QUESTION: i have 2 mickeys and 1 red wag and they tend to rub thier bellies on the rocks at the bottom of the tank, why do they do that? i have also seen one do that then dart around and come back and do it again its kind of funny but i dont know why they do that any insight? thanks

ANSWER: Hi Amy,
Does it look like they are itching?  Do they suddenly dart at the gravel, decorations and ete...then come back and do it agian?  If so they might have a parasite on the skin, like Ich.  If not, I'm not sure why they do that.  Haven't seen platies doing that.  
-Matt-

---------- FOLLOW-UP ----------

QUESTION: how would you tell if they had a parasite, no this one doesnt seem to just dart at any thing in particular, also the red wag like to bury its self in the coral formation like its sleeping alot of the time it it lonely?

Answer
If they had a parasite on the skin, they would swim next to an item and dart and rub on the item with its side to relieve the itching; the side that he is itching on.  

I dont think he is lonely.  The only fish that get lonely are the schooling fish that do not have enough of its kind.  Platies are not schooling fish.  I dont think its anything to worry about.  Be sure to do water changes weekly to lower toxins in the tank.  15%-20% water changes.