I was looking around About.com and saw this guys tank. I havent seen these fish ever being put in a 29gallon and was wondering if it was overstocked...
That's what I was thinking . The yellow shouldn't be in and there and the purple tang . I'm not sure what that little one is called though (not the chromis). I think its a type of Goby.
That is overstocked. Yellow tangs and Regal Tangs both are far too large for a 29 gallon system. They grow half it's length, for one.
The "Goby" is actually a Cleaner Wrasse. This fish is either easy to keep, or quite literally impossible to keep, depending on the specimen one aquires.