Bettas in a Divided Tank

I have two of my bettas, Captain Morgan and Mai Tai, in a divided tank. [See signature.] It is filtered and lit, and stays at roughly 76 degrees.

When I first put them into this tank about 2 weeks ago they were perfectly fine with each other. About 5 days ago they were both missing chunks out of their tails. I came home today to discover an even larger chunk out of Mai Tai's tail [making him look like a lyre-tail] and most of Captain Morgan's tail munched off. There's about 1.5-2cm left of it, and it used to be HUGE.

Any ideas? Their tank is separated with plastic craft canvas. I'll attach a picture. The green plant in the right side is no longer in there, I traded it for a big broadleafed plant that blocks most of the divider, figuring that it'd stop their chewing of each others' tails. Then I came home and more tail is gone.

I've been treating them with Melafix and salt.

This is what Captain Morgan's tail used to look like.. You can see Mai Tai's in the last picture.

i have a similar set up, except with the more traditional divider that you can buy at the lps. kyuck's tail looked a little ragged last week, so i added salt and a little melafix and it looked better, but today i noticed chagi's tail is really ragged. it looks like they may have bitten their own tails, b/c i don't think they could get through the divider at each other. i am thinking of trying the colloidal silver to help repair the damage.
was the tank cycled when you added them? reading the last few threads, it really seems like altered water quality could affect the fins, maybe if the tank is cycling that is making it more apparent.
i'll be watching this thread for some ideas as well!

They can see each other, and want to fight. Since they can't chew on the other betta, they chew on themselves. Some bettas chew their own tails when they have been carded for a few minutes. I can understand why these did , since they see each other all the time.

It's not that easy for them to see each other though. It took them a couple days of being in there to even notice that there was a betta on the other side.. And with how much is missing off of Captain Morgan's tail, it doesn't look like he could've chewed it himself. One part of it is barely a centimetre long!

I wouldn't have thought it was because of them seeing each other, because when they were in separate tanks they used to be right next to each other anyway. That, and a couple days ago I spotted a piece of Mai Tai's fin in Captain Morgan's mouth. Hmm..

The tank is not cycling, it used to be just an individual tank before I divided it. I kept the filter media and gravel and plants in my other tank so the bacteria didn't die off, so it's been instant cycled since I put everything back in.. I tested the water earlier and everything is zero with the exception of 10ppm nitrate.

I'd separate them but the only bowl I have on hand is probably the size of the one in the Betta-tech setups [the ones with the light on top], and I'd rather not put them into that.. I guess it's a trip to WalMart tomorrow to buy a new bowl.. *Sigh.*

If they can't see each other..exactly how is it they are getting ot each other then?

I'm confused about that...because it would make sense that they are doing it to themselves otherwise.

It's plastic canvas. It's not got great visibility, so I didn't think they'd be able to see that easily. I'll attach a picture of it from the side before I put everything back in it so you can see what I'm talking about.
I figured with the little holes, if they put their fins up against it [they both had a bit of a combtail thing going on] then the betta on the other side could grab that ray and start chewing. I just don't see how Captain Morgan's tail could've been chewed down that much by himself.
Either way, my best friend is taking me to the pet store in her car on Friday [yay, no bus!] so I'll see if we can drop by WalMart to pick up some big, cheap bowls.

Thats enough to know the other male is there. If you ever see a male wrap a female, you will understand just how far they bend. They could chew their tail to the bone if they wanted to. I have 3 males I can not card with other males. They chew their tails every time. I have to set a female beside them, to get them to flare. Then it's all about love, and not kicking butt. They are fighting fish. They should know it's their tail, and not the other bettas, but the urge to fight must really mess with their heads. I have seen it done till I know for sure these males do this, and have discussed it with many who have noticed the same thing with some of their males. Males in the same tank, even divided, is not a great idea. If the male happens to jump the divider, like alot of females do, there will be at least one dead betta. good luck.

I don't think that they'd be able to jump the divider, because it goes all the way to the top of the tank and there's a top on it.
..I didn't think they'd be able to see each other that clearly. S'okay, I think I'm just going to tear the tank down this weekend and put them in bowls until I rip all the silicone out. Then one of 'em can have that tank, and I'll put the other in a bowl. *sigh.* So much for saving space! lol