Ok you bet.
Im a bit surprised that no one has responded with a resounding "no, do not keep tangs in a 4 ft tank".

You can go to RC for that answer if you like...:lol:

LoL.
Yeah that did seem to be the general tone over there

Wow 9 years old!!!
Congratulations, that is quite a accomplishment.

My Yellow was 9 also whe she passed away. Again, with more care and less moves, I think she had a few more in her.

How big was it fully grown?

My tangs never grew beyond the size I bought them. Nothing noticeable anyway. My YT was typical pet store size, maybe 4" nose to tail?
I feed daily, broccoli, kale, nori and a variety of meaty bits, but never had a tang grow.

I keep a YT and a Powder Brown in my 90, both are doing very well, very happy, ive had the yellow for about a year and a half and the PB for about 2 months now!

I would suggest getting the book "Marine Fishes" by Scott W. Michael. Good info on 500+ fish. Worth the $25. This book mentions 4 or 5 tangs that might work in your tank.

Scott

When I started I didn't know about the 4 ft rule but I have 2 tangs in my 72 bow. Not
sure of the exact measure. I first had a yellow tang and It grew large and mean. Sold
him and got a smaller yellow tang. I also have a hippo who is growing by the minute. If
I could get the yellow out I would. I did have a book that tells you how many gallons are
needed that was what I went with. I also have a 95 gal with 3 tangs in it.