help with blue regal tang

[BarrySDCA]

I've had a blue regal tang in my tank for over a year now. The tank is 50 gal and well established. The tang is maybe 3" long.

For the last several days he has not been eating. He sometimes lies on his side and sometimes straight up, but is always hiding in the rocks. He is not eating. He has not lost his color yet (that I can see) but at this rate it's only a matter of time.

I see no obvious signs of any fish diseases. I'm trying my best to get a good look at him w/out stressing him any more. I've tried garlic laced seaweed....nothing.

Can anyone please offer some suggestions?

Thank you!

 

[leebca]

More info is needed:

How old is your tank? When did it originally cycle?
What kind of system do you have (tank volume, dimensions, bio-filtration method, the equipment you use, any carbon or other chemical filtration, kind of substrate, etc.).
List all specimens & sizes in the tank (fish, inverts, corals, clams, snails, crabs, shrimp, etc.).
If you have a refugium and/or sump, what is living in it?
Do you use a quarantine tank and procedure?
Foods you use and feeding schedules.
How long have you had this fish? If the fish was recently acquired (4 weeks), two more questions: Do you know what sea/ocean it came from? How did you acclimate it ââ"šÂ¬Ã¢â‚¬Å“ what procedure?
Do you use any vitamins? Fat additives? Any elemental or other additives? Please list all.
Chemistries ââ"šÂ¬Ã¢â‚¬Å“ please give actual numbers (Ammonia, Nitrite, Nitrate, Phosphate, Silica, Ca, Alk., and any others you have)
Water parameters ââ"šÂ¬Ã¢â‚¬Å“ please give actual numbers (pH and your pH range, salinity or sp. gr. & range, temperature range)
Do you see any of the following in your system: hair algae; micro algae; cyanobacteria growths; dinoflagellate (zooxanthellae) growths; brown algae; diatom growth; slimes; colored patches on rock or substrate; etc.?
Water changes (how much and how often). Kind of artificial salt youââ"šÂ¬Ã¢"žÂ¢re using. Kind of source water you are using? Have you analyzed your source water for the above chemistries? When did you do these tests last? What is the TDS of your source water?
List what you added or taken out of your aquarium system (living, decorations, and equipment) during the past 6 weeks.
Maintenance schedule. What have you done lately