So, the original picture from aquabid that I got him from shows him like this:
And he has come close to looking like that, but right now, he's looking like this:
His water parameters are fine and his tank is cycled. I noticed his fins started becoming a little see-through after putting in a second (canister) filter. It was very small and shared a pump with his sponge filter. Today I took it out and made the airflow of the sponge filter very weak, to see if maybe the water movement has been stressing him out. He does look a tiny bit better but not that much. I do have information on what conditions the breeder had the betta in, if that's needed.

And he has come close to looking like that, but right now, he's looking like this:

His water parameters are fine and his tank is cycled. I noticed his fins started becoming a little see-through after putting in a second (canister) filter. It was very small and shared a pump with his sponge filter. Today I took it out and made the airflow of the sponge filter very weak, to see if maybe the water movement has been stressing him out. He does look a tiny bit better but not that much. I do have information on what conditions the breeder had the betta in, if that's needed.