Why is my comet goldfish scared ..

Brief：
Im having a severe issue with my comet goldfish.I have a penguin air filter in a ten gallon tank. the fish is kinda large (4-4 1/2 in), so weve been h.. 

Im having a severe issue with my comet goldfish.I have a penguin air filter in a ten gallon tank. the fish is kinda large (4-4 1/2 in), so weve been having some cloudiness in the tank.I decided to add an air stone to increase circulation and also added a small filter that attaches onto the inside of the tank to help with the waste produced.My fish seems really scared.He just sits in the corner barely breathing when either the small filter or the airstone is on. He will sit on the bottom of the tank on the opposite side. The problem is, it was REALLY helping with the tank cloudiness issue.Im a beginner at fish care. His water tests normal for levels. I just cant find any info as to fish being scared of air stones, or vibration. HELP! And please,dont rag on me for getting a fish I know nothing about.lol. He was rescued from a very abusive home.

When I first got my air stone my fish did that.They acted as if they were afraid of the bubbles.In time they got used to it and now have no fear.Give him some time he will stop being afraid. Goldfish have a memory of 3 seconds, so if he's scared, he won't remember. But if you are worried, maybe you should ask a pet store. Your fish might be ill. Not because of the filter or the air stone. Test the pH of the water, the temperature ( the filter might be heating it up ). Add a few aquarium plants if there are none. some fish can be scared of air stones. As for your cloudienss I would reccomend a bigger tank. Goldfish should have 2 gallons of water for every inch of fish so he's just at his limit in his current tank. He will eventually reach 12-18 inches in length. Another thing that will help with your water is only feed him once a day and only enough so that it is all gone within about 10 sec. Many people over feed fish, they have a 3 sec memory and will forget they just ate, causing them to overeat. if your using flake food try pellets, their easier for them to get all of the food so it doesn't sit on the bottom. I would day about 3-4 medium pellets a day. If you still feel that you are not feeding him enough.You could give him treats at night or morning (whenever you're not feeding him). Gooldfish love peas and orange slices. I thaw out frozen peas in hot water then drain them(only give him about 3-4 when you give him these) Just cut up orangslices. Make sure to remove any access peas or orange within 20 min. This will keep the ph from rising.

I have 2 koi, one is 10inches, and I have 4 comets about 5 inches long, they all love their treats.