scubasteve06
Jeeper Reefer
I agree with you, the OP should have done way more research and taken it much slower, but I don't agree with your broad statements.
Everyone's tanks are very different from each other and what is true with one tank wont be true with another. As an example I have never quarantined a fish in the five years I have been in this hobby and I have never dealt with ick, or any other parasites. Now if I got my fish from Petco instead of my great LFS I would definitely want to QT my fish.
Saying a fish needs a certain size of tank and wont do well in anything less is wrong imo. If a fish is eating, active, and shows no signs of stress or illness what more could you ask for. You cant quantify happiness in fish and we have no idea if a yellow tang in a 400 gallon tank is any happier than my yellow tang in my 55 gallon if they are both eating, active, and show no signs of illness/stress. However the OP's fish are showing signs of stress/illness and are not suited for the tank they are in.
You are in a for a disaster one day by not Qt'ing your fish, and there is nothing more to it than that. I don't buy my fish from Petco and I still QT them. You will be sorry for not doing so one day. Maybe not yet, but one day you will understand.
You are also naive thinking that a fish in a 400g tank is no happier than a fish in a 55g tank. There is a reason people who aren't 16 yet can't have a liscence to drive, just like there is a reason there is a size requirement on tanks for certain fish. It's that simple, for you to think that way is just plain idiotic. If and when your tang lives to be 5 years old (which I highly doubt seeing as you don't QT and keep it in a way undersized tank) it will be close to 6" and will be a terror in your tank. I had a 3" one in my 125g and it wouldn't allow a single new fish to be added. He paced the 6' of my tank all day long and 'flashed' everywhere. Seriously, you need to go grab some books like I told the OP to do and read about minimum care guides of the fish you are keeping. If you think a Sweet Lips which grows to 2' long, a PBT and a Sailfin tang which both get 10" long not to mention the sailfin will get as tall as it will long, you need to leave this hobby. Any moderator, or member that has any more sense than you or experience in this hobby (years don't count, especially in your case) will tell you to go head back to the new to the hobby section and take a refresher course.
I am going to leave this thread now before I say something that will get me in more trouble than this post probably will.