Betta fish, Sick?

[Kisa]

I recently got a new Betta fish male. I bought him a 5gallon, with live plant, and a fake rock decor. The water I used for the tank was from my 50gallon established tank. I let the tank cycle for at least 6 hours... (during this time my Betta was still in the cup I bought him in, in my bathroom in the dark)... Then put him in.
Over the next few days, he is acting normal, and seems very aware of everything, but I noticed something strange on his head. I do not know if it is a sore/wound, or just some bad breeding.
I also noticed, his fins are starting to slightly bend (mostly the bottom), and the top dorsal is curling a lot more.

Please and thank you, I love this lil guy~

----Tank Info----

Tank: 5.2 gallon; Imagitarium Cube
(comes with built filter)
Heater: 2-10gallon; Tetra HT10 50w
Bubbler: 5g pump, with small air rock
(I only use it in the farthest back corner to move water around a bit)
Thermometer
Live Plants: Marimo Ball & Amazon Sword
Fake Rock Decor with fake plants attached
Natural colored gravel
​

My Fish-
YouTube video
^^^^^^^^^^



SEMI DECENT PICTURE OF REDNESS ON HEAD

 

[Angellove783]

Hi Kisa, one question I have is Did you add anything from your established filter to your betta's tank filter? You should. And another thing to make sure of is to not have the water push him around all the time. It makes these little guys over work on trying to swim. He could have hurt himself on something and nicked his head. Or could be ammonia getting too high in the tank if it's not cycled. You can dunk your filter sponge/cartridge into the betta's filter and cycling would be done. If you shake enough good bacteria off into his filter. Keep an eye on him watch to see if he could have hurt himself on something. Hope things get better.

 

[yanagi]

Yes I agree it looks like he might have hit his head on something be sure to keep your water really clean

 

[King Fisher]

First thought is ammonia poisoning