About a week ago, one of my family members adopted Caroline, a sweet, curious little girl. We both love her so much. I told my Caroline owner to change the water in the the bowl ( 1 gallon) about every day, but when I came back a few days later, the water was a bit dirty and Caroline was hiding under the rocks added to her bowl. I asked my family member if she soaked the rocks in warm water, and she answered no. She is new to betta keeping, so I don't expect her to know everything.
At first I thought Caroline was just trying to hide, since I read they don't always like to be out in the open. So I went and bought some supplies to build a little cave with rocks. Then I realized Caroline had a lump on her side, near her tail.
I'm afraid Caroline's life depends on this, so help is appreciated! Thanks!