Well,
I have 2 black Aro with 180 gal and they have something about 1,5 year. They already completely fine, but I see that they really need more space.
It is not only space for your fish. When your fish will grow up, he will be produce lots of waste. In my opinion this can by a bigger problem because you will have high nitrate level (then ammonia) and you will have to change water 2 times per week sometimes 50%. It is not good for fish (stress, hesitate temperature and other parameters of water).
You can keep your Aro even 2 or 2,5 years in 180 gal tank, but it depends about fish. I'm sure that you will see when your fish needs more space. I see it, and I start thinking to change my tank.
Good luck !