EDIT: Please offer some advice guys, I know I need to be patient, but the longer I wait, the worse the situation gets! EDIT: The membrane has receded further, and one of the rays has receded too. I haven't given him any more medication, I'm doing daily water changes, and the results of 3 water tests with 3 different kits have all told me the water conditions are fine. The temperature is also steady. He's active, colourful, and eating well, but his fins are not improving! Is it possible he's developing a crown-tail? I've literally tried everything, and nothing is helping him, it's really stressing me out seeing him this way. Hi, About 2 weeks ago I introduced a new Betta to my tank. I don't think I've edited the stats for this tank yet on my profile, but it's essentially the same as the one old one. I forget the make, but this tank is 6-7G, and I cycled it for 5-6 months. I did the same cycle as I did with my other tank, which has housed a happy Betta for about 3-4 years now. I added fish food to get the bacteria up, etc, etc, everything spiked, then dropped to normal levels. I checked the levels for another few weeks until I was sure everything was safe, then I went out and bought the Betta... (if you need any more info about the cycle just let me know, but I've checked the ammonia/nitrites/nitrates twice in the last hour and they're all at good levels.) For 2 weeks, he has been absolutely fine. I did a water change a week in, and he's on a diet of Betta pellets and bloodworms. I got home today at about 4:00pm, and he was still fine. It's now 7:50pm, I looked at the tank about 45 minutes ago, and his fins had... well, I'm not sure! The rays are all intact, but the membrane has receded. I can't take any pictures, but this looks a lot like my Betta's fins: http://www.tropicalfishkeeping.com/userpix/616_IMG_01572_1.jpg I've done a 60-70% water change, and treated the tank for fin rot. The fin's don't seem to actively be decaying right now. My question is, is this fin rot? Could he have ripped his fins on the filter? ...I had someone suggest he may be a crowntail, but I thought the tail was already crowned at birth... There are some silk plants in the tank. I did the 'pantyhose' test to check if they were a threat but honestly, they're all very soft. And the way his fin's look, it doesn't seem like they got caught on anything. The filter current isn't that strong either so I'm pretty sure that's not the cause. The only reason I can think of is fin rot, but I didn't think it could develop that fast, and the conditions in my tank wouldn't promote it at all. Any advice is very much appreciated!