I don’t think it’s my water quality because I’ve only had this betta in a 5 gallon for over a year and the tank has been cycled for around 1.5 years. My filter intake is covered by a sponge and my output is also covered by a sponge to slow down the water flow.2 years isn't very old for a betta, and torn fins aren't usually a sign of aging. They might get a bit tattered, but not necessarily torn.
What's your water quality like? Can you have it tested? Is it possible your filter could be doing some damage to his fins?
I had a Dumbo Halfmoon make it to 7, and his fins never really got torn or anything like that. Near the end, his back hunched, his color faded, and he had a few tumors, but he never had torn fins.
I think it must be bad genetics then because I got him from a pet store. He was probably sold when he was a year old.I did notice more broken rays and torn fins in one of my old long finned bettas, as well as paler coloration. Before he was euthanized by an aquatic vet due to an internal tumor, his fins seemed to tear more easily and this was even after I removed/ sanded down the decor. I suspect as the tumor grew it stole nutrients his body needed for repair of minor injuries- just a theory. Lifespans of bettas are anywhere from 3 years to 5 or more ( 7 is amazing- that fish must have had optimal care!), and most aren’t sold until they are 6 months to a year old. Also, how quickly a fish ages may have to do with genetics and conditions and stressors that he experienced before you even took him home! In my experience trying to predict the lifespan of a betta is a **** shoot
I do a 20% water change throughout the week, I pretty much top off the tank when ever the water level is down. I measured one week and it ended up with me adding 1 gallon of new water to the tank per week. I feed Betta Bio Gold by Hikari 5 times a week and I do freeze dried bloodworms 1 time a week. My betta doesn’t eat in Sundays.
His fins don’t look like they are bit, they are torn but I don’t know why they are tearing. The fins don’t look ragged from biting, it is clean slits in the fins.Might be possible he a late developing fin biter. Pay attention to stuff like if he flares at his own reflection, chases his tail, stuff like that. Flaring at his own reflection is usually what seems to trigger my fin biter.