I noticed the other day that Orchard has very very thin stringy ventral fins now. The ventrals are the pair that hang down below his stomach, right?

I've had him for almost a year. Is this part of aging or could it be something else? I use softened water for my fish tanks, so maybe he's not getting the nutrients from the water he needs..

All their fins get a bit limp and stringy as they age, I find.

Weak ventrals are also a sign of lack of waterchanges as fry or something... I have whole batches that have them and those that don't.

Thanks Yabbie, that is probably it. I rescued him from poor conditions at a chain store and his ventrals were never quite right. He came home with rot and as his fins healed (his ventrals which were bent oddly) fused into weird bent angles.

He's still got lots of time to live, right?

Isn't the average age for a Betta three years?

Yeah, or two years. It's similar to the average for a goldfish and we know they live 10+ years if treated right.

Bettas can live to around 5 years but if he's already had finrot, been raised in poor conditions etc, he may deteriorate faster as he ages and be an average statistic.