30 Gallon Tank My betta fish's fins have suddenly deteriated overnight

My betta fish ponyo's fins seem to have been damaged somehow sections seem to have just died ininitialy thought it was fin rot but it looks very differnt to any cases ive seen. There was no sign of any of this yesterday it seems to have happened overnight but im not sure how. What does this look like to you guys?

Just some details that might be important he's in a 30gallon long cycled tank with 9 glowlight tetras, 4 kuhli loaches, 1 bristlenose pleco and a mystery snail. It is decorated with drift wood, maple leaf rock and is is fairly heavily planted. He hasnt been acting strange at all and is still very active. There is no fin nipping going the tetras leave him alone and he leaves them alone. I do weekly water changes of 40%-50%.
Heres some pics the damage is quite obvious also he has always had curls in his fins those arnt new the first pic is of him 2 days ago

 

Looks like fin nipping to me. I have a hard time believing that the glow light tetras don't nip your betta. Tetras are some of the more nippy fish as it is how they interact together socially, which is why I wouldn't put tetras or guppies in with a long finned betta. The glow lights are my first suspect.

The other possibility is your betta nipped his own fins. Usually this is caused by stress which could be from the tetras. Alternatively if your flow is too strong for your betta that could also cause fin nipping as your betta will have a hard time swimming.

I'm against keeping long finned bettas in large tanks for this reason. 30 gallons even in a long footprint is still a deep tank for a betta. Considering they need to constantly visit the surface to breathe, it's a lot of swimming. It's the equivalent of trying to run a marathon with a parachute on your back. Fancy tailed bettas really should be kept in tanks under 20 gallons, preferably 5 or 10s. Plakats do much better in larger volume tanks as they are more active for the reason that they are lacking heavy finnage.

I still think it's the tetras though tbh.

Edit: just thought of another scenario. Is it possible he got stuck to your filter intake? Sometimes bettas with long fins get stuck to the filter intake which will damage their fins. I recommend a sponge pre-filter that slides on to the filter intake which will keep shrimp, fry, and fish safe.

I would make sure your water parameters are tip top until his fins start to heal. Otherwise rot will become another issue for him.

 

I know its too big for a longfin ive already been looking for a new tank for him. I do have a hang on filter but the intake dosent have a super strong pull so i doubt thats the cause. Is it possible he might nip his fins because there too heavy? His fins have grown a lot since i got him and if he he sits in one place they pull him down (which is why im downgrading him). I wont be able to get a new tank for at least 2 weeks for money reasons and then id have to cycle it but ill definitly get him a new tank. For the time being ill make sure the water paramaters stay good and keep an eye on him. Thanks for the advice

 

I know its too big for a longfin ive already been looking for a new tank for him. I do have a hang on filter but the intake dosent have a super strong pull so i doubt thats the cause. Is it possible he might nip his fins because there too heavy? His fins have grown a lot since i got him and if he he sits in one place they pull him down (which is why im downgrading him). I wont be able to get a new tank for at least 2 weeks for money reasons and then id have to cycle it but ill definitly get him a new tank. For the time being ill make sure the water paramaters stay good and keep an eye on him. Thanks for the advice

I definitely would set another tank up if you are able! I think having his own smaller tank would be much better for him in the long run. If you can, get your filter media for the new tank now and run it in your current filter. That should seed enough bacteria to somewhat instant cycle your new tank just do not add any other livestock other than the betta for a month or so. Maybe in the meantime if you don't already or even if you can't afford to get him a new tank in the near future, situate some plants at the waters surface or get him a betta leaf so he has a place to rest at near the surface. That should definitely help him with swimming exhaustion and also to give him a place where he can stay away from the other fish but easily go and get a breath of air. I'd suggest a few bunches of ancharis for this. It's a bulletproof plant with no special requirements and can grow floating. Toss it in and I guarantee it will become his new hangout/resting spot!

Self fin nipping is mostly a personality thing but stress, swimming issues, and shipping in bags also trigger fin nipping in bettas. Some will nip their own fins in any given environment, some only do it situationally.

 

I currently have ambulia thats grown

I definitely would set another tank up if you are able! I think having his own smaller tank would be much better for him in the long run. If you can, get your filter media for the new tank now and run it in your current filter. That should seed enough bacteria to somewhat instant cycle your new tank just do not add any other livestock other than the betta for a month or so. Maybe in the meantime if you don't already or even if you can't afford to get him a new tank in the near future, situate some plants at the waters surface or get him a betta leaf so he has a place to rest at near the surface. That should definitely help him with swimming exhaustion and also to give him a place where he can stay away from the other fish but easily go and get a breath of air. I'd suggest a few bunches of ancharis for this. It's a bulletproof plant with no special requirements and can grow floating. Toss it in and I guarantee it will become his new hangout/resting spot!

Self fin nipping is mostly a personality thing but stress, swimming issues, and shipping in bags also trigger fin nipping in bettas. Some will nip their own fins in any given environment, some only do it situationally.

I currently have ambulia thats grown across the surface of the tank which he rests on and because of the placing of the driftwood theres lots of resting spots right by the surface that he uses and ive ordered 6 betta leafs online (a little exesive but it was only like $5) and ill look into buying some ancharis once he has a new tank set up i should have enough money in a couple of weeks so hopefully he'll be fine till then. I have 2 bags of filter media in the tank at the moment that i got from a freind back when i set the tank up so i can use those to cycle a new tank.

 

I currently have ambulia thats grown

I currently have ambulia thats grown across the surface of the tank which he rests on and because of the placing of the driftwood theres lots of resting spots right by the surface that he uses and ive ordered 6 betta leafs online (a little exesive but it was only like $5) and ill look into buying some ancharis once he has a new tank set up i should have enough money in a couple of weeks so hopefully he'll be fine till then. I have 2 bags of filter media in the tank at the moment that i got from a freind back when i set the tank up so i can use those to cycle a new tank.

Hmm, seems like that is all good then so I would definitely assume either he nipped his own fins from possible stress or it was your tetras. It's good that he has a place to hide though! It will be hard to pin down who did the nipping until you eventually are able to isolate him to his own area. For now keep track of his fins via pictures so you can tell if there is more loss or growth starting and when you have time sit and watch the tank for awhile and monitor how everyone interacts in the tank.