Yellow Tang acting strange?

[minihero]

Hi i have a 300ltr tank and my levels are amonia 0, nitrate 0, nitrite 0, and ph 7.8. Today i have noticed my yellow sail fin tang is acting strange, it has spent all day hinding behind my rocks darting back and forth, in the area it is doing this there is the pickup pump for my protein skimmer, this is very out of character for it as it is usually around the front of the tank following the coral beauty, i think from what i can see of it there are slight pinkish discolourations on his body, it is a peaceful tank with only 2 clown fish, a fire fish and a coral beauty as well as two shimps, the tank is about 4 months old an the tang was the last added about 3 weeks ago.

The only corals in the tank are one tree polyp and a finger coral, any comments or suggestions would be much appreciated thanks.

 

[Floyd R Turbo]

What you are describing sounds similar to what happened on a tank I 'rescued' back in May, about 3 weeks after I put the Yellow Tang back in, I think the lights got left on overnight and the next day he was darting all over the place, and died. His fins turned red. If you google that, you will find that this can be stress induced and diet induced. He wasn't being fed good food, and I believe this led to his demise. Yellow Tangs need Nori daily or else they get nutrient deficient and freak out. If the fins are already red, it may be too late (hemorrhaging) but get some nori quick and start feeding daily. Also frozen nori cubes are good, or the green flakes (can't remember the term, veggie flakes basically)

 

[cmor1701d]

Is this a Yellow tang (8" / 20cm) or a Sailfin tang (1'+ / 38cm) ?
Neither should be in a 300 ltr tank as both require 100g (454L) and really should only be housed in a 6' (182cm) or longer tank.

It could be as Floyd suggested either stress or diet related.