lost powder blue...but why?
 

I got my powder blue about 4 1/2 months ago, suprisingly he did great, no ick nice and fat and got along with my other tangs. After coming back from vancouver last week I found him to be extremly skinny, lethargic and not eating. All the other fish seem to be fine, except him. What can cause a fish to decline so much in 2 days when he was fine? I guess theres probaly a number of things but just upset by losing this fish, seeing as he was doin so well. Whats you expirence with the PB? thanks alot

tb

Most likely the fish you bought was from the Philippines or Indonesia where the use of cyanide is rampant. Insist on net caught fish which are available.
The powder blue tang is a poor choice with a poor survival experience.
Here are the tangs to avoid.
http://wetwebmedia.com/badacanthurusaq.htm

If your fish was doing fine and eating well for several months, I would doubt a sudden downward spiral was due to cyanide. Also, I don't think PBT are poor choices. Many aquarists keep them quite successfully.

Were there any signs of disease on the fish - and in particular lacerations, cuts, or haemorrhages? Tangs, and PBTs in particular, can be quite aggressive and scrap a lot. Often such behaviour is delayed and can appear if a fish gets larger and suddenly challenges the pecking order status quo in the tank. If your PBT got into a fight and was wounded, it's very possible that a septicaemia (basically and internal bacterial infection) caused it to go downhill very quickly and die. Just a guess of course. Other issues such as nutritional deficiencies are usually chronic and progress slowly. A toxin or poor water quality, which can cause your fish to go down fast, would normally affect more than one fish. So I would probably rule both of these out, leading me to suspect an internal bacterial infection.