I bought two goldfish last summer and they've been doing great in my 10 gallon tank, but I am starting to wonder about one of the goldfish. I don't know if he is sick, in pain or what.
When I bought these goldfish, one looked normal with skinny body and the other had a bloated or ballooned stomach. I thought this is how these goldfishes suppose to look and never really gave it a second thought, but now I am thinking he is sick.
Bloated goldfish doesn't look or act like he is sick. He is swimming all over the tank, foraging for food. At feeding time both of them swim really fast to the top of the tank and eat all of their food, he is pooping regularly, etc.
I regularly change the water, clean and replace the filter. I would like to know whether he is sick, and if he is what should I do?