When should I upgrade my fish to a larger tank?

[TheFishBoys101]

Hi, I recently bought a tank off craigslist and it came with some fish that would eventually outgrow the tank. It is a 120 gallon, 4 ft long, 2 ft wide and 2 ft tall, and the fish that I know will outgrow it are a blue tang and a porcupine puffer. The blue tang is about 4" and the puffer is about 5" currently, and I was wondering if anyone knew at what size I should upgrade them. Please let me know, thank you!

 

[drains05]

They need a minimum of 6ft by 2ft for swimming room.

 

[TheFishBoys101]

They need a minimum of 6ft by 2ft for swimming room.

Yes, thank you, but at what size should I upgrade them to that?

 

[TheFishBoys101]

Yes, thank you, but at what size should I upgrade them to that?

What size of the fish is what I mean

 

[Squidward]

ASAP