Betta fins fading/browning in patches

I got my betta (Bean) on December 31st 2022. He's very active and eats as much as he can, the only thing is his colour seems to be fading in patches and he's developed a chunk out of his tail.
I'm not sure if the Browning is just him changing colour as it seems as if he's got a patch on his body as well, although I do think his find are a bit faded. The patches don't seem to be fluffy or anything.
He is in a 15 gallon (60 litre) tank with 2 Corydora and sone snails, so nothing that could be biting his tail. He unusually gets fed dry food ( betta pellets, bug bites, hikari vibra bites) around 3-5 pellets a day. He also occasionally gets frozen food, although not often. He also gets 1 or 2 fasting days a week.
I try and do water changes once a week although admittedly I haven't been very good at that recently. I did a big water change today.
Last time I tested my tank parameters were:
Ammonia: 0
Nitrite: 0
Nitrate: 5
Ph: 6.5-7
I'll test again today or tomorrow though.

Please excuse the algae in the back of the photos, they were taken before the water change.
Any advice on what this may be and what I can do would be much appreciated, thanks in advance.

At the minute I think I'll try and do a couple of small water changes throughout the week to keep the water clean, and add in some more catappa leaves.

 

At the minute I think I'll try and do a couple of small water changes throughout the week to keep the water clean, and add in some more catappa leaves.

See! You already answered your own question. Clean water, clean water. Bettas best buddy.

 

Okay so first, your betta is a female I don't see anything in her colour that looks off. She's a marble and they change regularly, sometimes within a day or two. The missing chunk on the tail does look like a bitten patch but could have torn. Hard to see the edges well in your photos to see if healthy edges or not...do lots of water changes, add some salt and the IAL for now and watch it closely.

 

Okay so first, your betta is a female I don't see anything in her colour that looks off. She's a marble and they change regularly, sometimes within a day or two. The missing chunk on the tail does look like a bitten patch but could have torn. Hard to see the edges well in your photos to see if healthy edges or not...do lots of water changes, add some salt and the IAL for now and watch it closely.

Are you sure they're a female? They were sold as a plakat male, how can you tell if they are female? Thank you very much for your advice

 

100% positive. I bred koi plakat bettas for years, pretty good at sexing them. It's her shape...very round belly, short ventrals, very short fins even for a plakat, overall shape. Stores screw up the sex of plakats all the time.

 

100% positive. I bred koi plakat bettas for years, pretty good at sexing them. It's her shape...very round belly, short ventrals, very short fins even for a plakat, overall shape. Stores screw up the sex of plakats all the time.

Thank you very much! I had been a bit worried about the rounder belly so glad to know it's nothing to worry about. Thank you very much for letting me know, I had no idea!

 

Nothing to worry about on the belly front You're welcome!

 

That does look like a bite on the tail. Hope she isn't nipping her own tail, that can be a fun problem to try and stop...

 

That does look like a bite on the tail. Hope she isn't nipping her own tail, that can be a fun problem to try and stop...

Yeah I was thinking about that. I really hope she isn't

 

I've never had a plakat that was a fin chewer, it's very unlikely. Long finned bettas usually chew their fins when they are way too long and heavy for the fish, which is obviously not an issue for plakats. Plus with fins that short it would be a real effort to self nip lol.