ph & sick fish

Question
Dear Stephanie,
I'm worried about my new fish.  Four weeks ago I purchased Black Noor fish (the fantail black goldfish with the bubble eyes) from a reputable store in my area.  I had him in a hospital tank for a week that was filled with water from the main tank before he joined my two fantails in the main 10 gallon tank.  I was worried about him from the beginning as he spent a lot of time hiding in the plants and his dorsal fin stayed flat against his body.  After the first week or two he seemed to get the hang of the feeding routine and mingled more with the other fish. Then about five days ago I noticed he wasn't swimming alot and spent most of his time hiding in the plants resting up against a leaf so he would just sit there and not have to swim at all-though he displays no bouyancy problems-and his dorsal fin is again flush with his body.  He still comes out to eat and forages about the gravel afterwards but then goes right back to his hidout in the leaves.  This is a relatively new tank setup, probably 6 weeks old at this point.  I've quite a few plants-I added three new plants right around the time I bought this new tank, but have a filter, airstone and light of high quality, I do 1/3 water changes every 10-14 days or so and suction the gravel every 4-5 weeks.  On the recommendation of my local aquarium store i switched from Tetra brand "sinking granules" to Aquatrol brand 'spirulina 20' food.  The only thing out of the ordinary I can find is the ph level has risen from 6.5 to 8.0 since I last checked it 4 weeks ago.  There's no evidence of disease or parasite and the other fish seem healthy and happy.
what's wrong-if anything-with my Noor?  Is it possible he's just depressed?  Is the new food not good for him?  Please help he looks so sad!

Answer
Hello,

I'll start with a couple recommended changes in your tank maintanence routine. I recommend you change 15% of your water every week, instead of 1/3 every 2 weeks. I also recommend you syphon your gravel every week as well. Everything else (including the food) sounds just fine.

If your fish continues to act like this, it may be a disease (likely bacterial). If he shows any other symptoms such as loss of appetite, loss of color, bloating, wasting away, swollen eyes ect. then you should treat right away. If you want to treat him, I recommend a product called Melafix.

I hope this helps.

Regards,
Stephanie