Hello. I have a grey and blue female platy in my ten gallon tank that I am worried about. She is staying at the top of the tank. Her belly is bloated and there seems to be a reddish patch on it. She's breathing a bit heavy, but her fins are fully out. She also doesn't have any buoyancy issues: she can swim to the bottom just fine. She's also not eating. I have three hypotheses on what it could be.
1) She's pregnant. I also have an orange male platy, and her belly looks a lot like a pregnant platy's baby. However, I don't think that being pregnant would stop her from eating and cause her to hang out at the surface. Also, I don't think the babies would have enough color to change the female's belly color.
2)Internal bleeding. The reddish patch on her belly, to my untrained eye, looks like it could be internal bleeding.
3)Constipation: The reddish color on her belly is close to the color of her poop. She also isn't eating, which may back up this hypothesis.
I have a ten gallon tank that is kept at 80 degrees.
The water is changed once a week (about 30-50% of the water taken out, and the gravel siphoned)
The ammonia levels are fine, but I haven't been able to get the water tested for anything else
The other two fish (One male platy and one betta) are both fine.
The symptoms started about a week ago.
Any advice you can give me would be very helpful.