Bala shark not eating

Question
We have a bala shark thats around 4 yrs. old.  My question is, for some reason all the sudden he is not eating at all! This has been going on for acouple 3 days now.  We did a half a water change in that time, and this is when I noticed after that, he was not eating.  He just swims around making the big O shape with his mouth, and swims right past the food.  He is usually a big eater.     Can you please give me some ideas what could be wrong.  We both love this fish,  and don't want to lose him.

Answer
Hi Barb,
Thank you for your letter. I recommend that you stop all feeding for several days. When you resume, feed one flake or pellet per square inch of fish. Also, buy a bottle of Cycle to treat the water. It's live friendly bacteria that will help break down fish waste and uneaten food. Follow the instructions on the label and keep it in the refrigerator between use.
You can read the full instructions at my web site:
http://steamboats.com/aquarium.html
Write back and let me know how it goes. Please do not use chemical treatments from the aquarium shop. They usually do not work, but only further pollute the water.
Nori