3 tangs?

[nereefpat]

My opinion to the original question:

The two blue tangs need 6-8 feet.

The yellow is fine, imo. The footprint of the tank is very similar to a 120 gallon. It can behave pretty nastily to any similarly shaped fishes, though.

The four Ctenochaetus spp mentioned above would also be good options.

 

[PatW]

I have a 6’ tank, 300 gallons. I have three tangs: kole, yellow and powder brown. All three tangs use every inch of the tank. I bet if it was an 10’, 500 gallon tank, they would use every inch of that.

I have other fish like my pair of fire fish that stick pretty close to their hidey hole. And these guys would be fine in a much smaller tank.

 

[mort]

- I mean - it can take years for a lets say 2 inch tang to grow to 6 inches (especially in an aquarium).

Depends on the species of tang. Zebrasoma are slower growing but a regal tang can easily reach 6" in a year-18 months, in a tank with enough space and food. They then slow down in growth but commonly reach 10".

I have never seen fish grow to their 'natural' size in a tank (including large tanks) very often - perhaps that because most die (i.e. in zoos, etc) before they reach 'full size'. In any case its an interesting discussion

Fish are less commonly seen at larger sizes in tanks because we seem to invent new ways to kill them off before they reach maturity, so I agree with you on that but you can see large specimens of most tangs pretty easily. I was offered a giant regal, sailfin, or naso most weeks when I ran a lfs.
Captive fish seem to commonly max out at about 80% of their wild size, or at least enough tangs, angels and larger species do to make it a rough rule. That means 10" for regals. The caveat on that statistic is space. You need to provide an environment where the fish can reach its potential and that means proper feeding but more importantly space. If we cram a tang into a small tank we can stunt their growth which leads to smaller fish and the likelyhood of health issues but just as important is not crowding them with competition.

So to everyone who I sold a tang to I gave the same advise, would you be happy and comfortable to have a fully grown (80% of wild size) tang in your tank. So for the op do you want a 10" regal, a dinner plate sized caribbean and a 6" yellow in a 4ft. That is their potential and the bases for your decision.