Betta: Shredded Fins. Help!

[mrstwalker]

I recently moved and now live in a place that runs off of city water. I purchased the API water conditioner (store was out of Seachem prime -- I hear that is the best you can get). I also transported all of my cycled media to jump start my cycle. I haven't been able to test the water parameters yet here (been here for about 4 days now) because all of that stuff got put in storage 

 I will probably be able to get my API master test kits back on Sunday.
 
So anyway, I'm new to chlorinated water and I hear that they add more ammonia to the water during summer months? So could their fins be torn up from that? It does not appear to be fin rot and it does not appear to be fin biting. I know that the 2 males haven't gotten into the other's side so I know it isn't from fighting. Also, neither fish appears to be sick. I couldn't get a picture of the veil tail, but the crown tail has the worst damage. Also, I know these pictures may appear to look like how a crown tail can look normally, but this guy below (Calypso is his name) normally has a very full tail. 
 
Please help! 

 

[gmc1]

Possibly the start of fin rot.if it is treat with triple sulfa or the likes.

 

[mrstwalker]

Possibly the start of fin rot.if it is treat with triple sulfa or the likes.

 
Even though one day their tails were fine and the next day they were completely destroyed like this?

 

[gmc1]

They could of been gradually getting smaller without noticing too much.until now.it may be something else but it did happen to me before.

 

[betta fish]

Can they see each other through the divider? I used to keep two males like this and they both tore their tails in frustration as they tried to get to one another, the change in position of the tank may allow them to see one another clearer.

 

[mrstwalker]

Can they see each other through the divider? I used to keep two males like this and they both tore their tails in frustration as they tried to get to one another, the change in position of the tank may allow them to see one another clearer.

 
Possibly. They are a bit closer to a window than they were before. The crown tail is much more aggressive than my veil tail. So maybe that's why he has more damage? I've always had issues with my veil tail's fins even though the water quality has always been good and has had the best care since I bought him, poor genetics I think on his part. 
 
If this is the cause of the fin damage, what can I do to prevent this? Putting them in separate tanks is not an option right now.

 

[betta fish]

I have read that crowntails are more aggressive for some reason, perhaps try some plants along the divider or diffusing the light a bit somehow adding some indian almond leaves may calm them down a little too and encourage them to build a bubblenest which may divert their attention for a bit.

 

[RainboWBacoN420]

Looks like tail biting...
My betta just began doing this. At first he had a little tear in his tailfin. I assumed it was from a sharp snaggy part on a piece of pvc pipe (that ive had no problem with it before) I had in there. The next day it was a huge tear. Then the day after coming back from work, his tail is shredded. Like completely shredded, I'll post a pic soon, but you can tell he was responsible for the shredded tail fin because you'll notice him twirl around trying to find his tail...
I'm doing water changes, and using API Stress Coat since my girlfriend said she had luck with it on her betta that was tail biting.
My poor fish though, man. :C He's a veil-tail and his tail was so beautiful.