Need Some Input from Experts

Last year, I produced some baby Okeetee corn snakes, and one of them got loose. I never saw him again. I had assumed that he was long dead, dried up in the corner of my basement somewhere, or that he had possibly wandered into the wrong bearded dragon cage or fish tank and had been eaten. Since then, I had gotten out of corn snakes and sold off all the babies and the breeding pair that produced them.

Today, over a year post hatching and at least 10 months since he went missing, I found a shed skin. This was the skin of a snake over 18 inches long. I had recently had an escape from a house snake of about that size, so I had assumed it was his. However, upon closer inspection, the skin clearly had faint saddle markings on the back, and head markings, which as near as I can tell, are identical to those you would see on a corn snake.

There are no wild corn snakes where I live, and the only other snakes I keep that have even remotely similar marking have never escaped (bull snakes and honduran milk snakes), so I think it's a safe assumption that this is the same little guy who got out last year.

The strange part is that from what I can tell from the shed, this snake seems healthy and while not huge for his age, seems roughly on par with a healthy growth rate, so he must be eating well. This is where I get confused, because with the exception of a brief mouse problem that we had for a few months (if he was eating them, he certainly wasn't helping to keep their numbers down, haha) the only conceivable foods that he would have ready access to are the following:

dried pellets/vegetables
dubia roaches
fish

The only one of those options that even seems remotely possible to me is the fish. I have a great many open-top aquariums in my reptile room, and I have been thinking lately that some of my fish were disappearing mysteriously, but I had chalked it up to them jumping out or dying or some other cause. There are certainly enough to keep a single yearling corn going, but I wouldn't have thought that a corn snake could hunt and eat fish with any degree of efficiency.

So, my question, does anyone know if a corn snake would be capable of surviving for an entire year off of little more than live tropical fish?

I have never had a baby or hatchling get loose. I did, however, have an adult corn get loose when I was in college. I found him almost a year (like 10 months or so) after he vanished. He seemed no worse for wear at all. No signs of dehydration or malnourishment. I did take him in for an exam and he did have some internal parasites. Which he didn't have before he escaped.

We have no idea what he ate or when/where he found prey. Or even if he brumated while MIA. We were just grateful to find him in the silverware drawer that morning.

My friend had a mex black king get out and found it one year later.