Who Gives A Fish Forums

Hey,
I've had my new double tail half moon betta in his 3.5gal tank for 4 days now, and I'm a bit worried. He's really active, but today I noticed the top of his double tail seems a bit clamped. The tank's got a heater, so the temp's around 77-78F, and I tested for ammonia this morning - 0ppm. The tank's been cycled for a while, so I'm not sure what's going on. Is this clamping a cause for concern? Could he be stressed? I've attached a photo from the day I bought him for comparison. Any input would be great, thanks.

It's gotten a bit worse since this morning, I just did a 25% water change to see if that would help.

"I'd suggest doing a pretty drastic water change, like 75% every day for the next couple of weeks to see if that helps alleviate the issue. Also, make sure to gravel clean the substrate daily to get rid of any debris that might be building up. And just to reiterate, always dechlorinate the new water before adding it to the tank. Keep a close eye on the ammonia, nitrite, nitrate and pH levels, do regular water tests. This should give you a better idea of what's going on in the tank."