Fish fighting?

Question
I have two female betas. The brighter one is Jasmine and the darker on is Brim. It appears that Jasmine; when ever Brim tries to eat; would puff out her gills. They chase each other around frequently in the bowl. Brim is starting to lose her color, i think that means dying. So i switched her to a well-water tank (its OK for well water right?) alone away from Jasmine. I don't know what to do. Petco says that they were both females. So I don't think it's actual fighting. It seems that in sperate tanks they are fine and Brim eats hungrily. Did petco lie; if Jasmine and Brim and actually to different genders, or is it like a alpha fight? What should i do? Should i keep them in separate tanks?
-Thanks, please answer with haste
Jacklyn

Answer
Hi Jacklyn,
Female Bettas are usually peaceful to each other, but there is always the chance of fighting, hence their name. My best suggestion would be to get a plastic tank divider (available at Petco), and use that to divide the tank. It doesn't restrict water flow, which is a nice feature. If you don't want to do that, you can keep them in separate tanks. Make sure Brim gets enough to eat after you move her; she's probably starving. I would also recommend getting live plants. They will promote natural behavior, and reduce aggression and stress.

Most Bettas sold in pet stores are males. Here's how to tell the difference; Male Bettas have long, flowing fins, while females have shorter, stubbier, less colorful fins. The employee may have been wrong, but usually they have been trained.

One thing that you must do: Well water contains minerals which may be harmful, etc. You will need to buy a water conditioner, such as AquaSafe or AquaPlus (available at Petco), to treat the water, to make it safe for fish. The well water may be causing the pale color.

Best wishes to your Bettas!