Tang in 40 gallon AIO

[JumboShrimp]

Sorry, "no".

 

[Bucrob]

If you really want a tang, get a tiny tiny tomini tang. They are the smallest tang and grow slower than other tangs.
I put a tiny one in a 45g tank 4 years ago and it still hasn't outgrown the tank. Its still only about 3.5" now. Great fish. Peaceful and grazes algae all day.
After 4 years it's still smaller than my female picasso clown for comparison, which is 6 years old.

A tiny tomini will not outgrow the tank for a number of years.

This statement is not entirely true. The growth of a fish is fundamentally reliant on numerous factors that some don't even take into account. The amount of food you feed, how often you feed, and the available algae to graze on.
From my own experience, fish kept in lower-flow systems often seem to grow slower. While that's anecdotal and there may be multiple reasons for it, my assumption is that they don't need to develop as much muscle compared to fish constantly swimming against stronger currents leading them to have a slower growth rate.

 

[Bucrob]

If you really want something to act as a nice color pop and a nice active fish, my personal favorite are wrasses. I have many wrasses, some being for utility and others purely for cosmetic purposes, but my personal favorite has to be a female Red Eye Solar Wrasse (Cirrhilabrus solorensis). It's not very commonly found in the hobby, but they are a beautiful fish and if you can find one don't normally cost too much (I believe they retail somewhere around the $80-$90 range). Mine was one of 4 fairy/flasher wrasses I added to my main 150g and I have never had an issue with her (my carpenter is a different story... he's a dou che).

Edit: the site really won't let me combine that last word... really

 

[Gumbies R Us]

You have 2 clowns correct? You still have plenty of room for a couple more fish.
Certain wrasse species, blennies, gobies, firefish, etc… a lot of options for you!

My advice to people has always been buy what will fit in your tank now, not “I’m going to get this fish now because I’m upgrading my tank soon”

 

[winxp_man]

I have 15-16 tangs in my 300 system.

Here is the growth on just the purple. Got it a year ago at about 2-2.5” it’s now 5” possibly just over 5”. I last measured it two months ago, and why I said possibly larger. My chocolate tang from 1.75” to 4.75 in a year and 3-4 months. If fed well tangs will grow faster than your think in the 5 inch range. Than a slowdown can possibly take place but hard to say. I just know that they can grow fast and it is an individual based thing to.

I’m my honest opinion I would only get one once you get a bigger tank.

 

[winxp_man]

If you really want something to act as a nice color pop and a nice active fish, my personal favorite are wrasses. I have many wrasses, some being for utility and others purely for cosmetic purposes, but my personal favorite has to be a female Red Eye Solar Wrasse (Cirrhilabrus solorensis). It's not very commonly found in the hobby, but they are a beautiful fish and if you can find one don't normally cost too much (I believe they retail somewhere around the $80-$90 range). Mine was one of 4 fairy/flasher wrasses I added to my main 150g and I have never had an issue with her (my carpenter is a different story... he's a dou che).

Edit: the site really won't let me combine that last word... really

I like these guys to.

Here’s is mine.