So I've had a betta for a couple of months in a 1 gallon tank. It had a cheap filter on it, and I think it stopped working for a few days - the water began to look pretty nasty, with an oily looking film on top. Then we started having problems.
Yesterday, he refused to eat. He would get a pellet in his mouth, but he spat it out every time. He started hanging around near the bottom of the water, and I thought maybe the water was dirty. I immediately bought a new filter and installed it. Also did a 75% water change before adding the new filter.
I checked the parameters before the water change, ammonia and nitrites are zero, nitrates were close to zero as well. Ph is a close to 8.
He did not eat this morning either. The water looks beautiful now, with no film on top.
What should I do? I do not want him to die.