When I had a silver I kept it at 79 Fahrenheit, got it at around 5-6", kept in a 120 over the course of maybe 6 months or so, it got to 13-15" and I got rid of it. The OP has year maybe year and a half in this tank if he takes care of the fish properly which he should plan to do, you shouldn't get a fish and plan to mistreat it to your benefit, your situation was obviously different, but I don't think you should recommend it, only share it. This is a tropical fish, so no it won't live longer at lower temps, the reason for slower growth and aggression not that silvers are really aggressive, is because you're causing the heart to slow down. Most people find their aros eat within the first week. I wouldn't recommend trying to slow growth by that much, that's like purposely stunting a fish which in turn purposely shortens it's life, your 4 month period wasn't to long but planning to do it for over a year is simply unfair to the fish, it's the OPs fish he'll do what he wants with it, but I don't recommend slowing the growth. Just my opinion. a healthy aro can grow 2 inches per month. So say 6 inches now, in a year+ it should be 2' easy, silvers are flexible, so depending on your dimensions you can get away with slightly longer but you'll see how crowded it'll look and I don't think you'll like it. Others have reported growing there's to 2' in a year from a small size.
