so i got Curly new years eve. he hasn't eaten since i fed him in his cup that morning. he is still continually hiding as well. well this morning i noticed that on the clearer part of his tail fin it looks blood red. its not at the very tip or on the edges but in the middle. any idea what this could be? his fins aren't falling apart either.
he's in a separated 10 gal tank with my other HM betta. there's a heater and a filter. any idea as to why his fin is turning red? did he maybe get stuck under something?