Female guppy health

Question
I have a ten gallon tank with 6 guppies (two female), one catfish, a lot of live plants and about 5 snails (that sneaked in on the plants when they were still eggs).

One of my female guppies had been chased by the boys a lot over the last few weeks. They didn't seem to be biting her, her body shows no signs of scarring. She had taken to hiding out in the thick part of the plants and has been hanging out there for the most part so the boys leave her alone. They are leaving her alone now, but I just noticed yesterday that all her scales, while they look perfectly intact and fungus free,   are flared outward (imagine a pine cone that has opened up to drop its seeds).

Is this an indication of illness, or do the scales open out like that due to pregnancy? She has been round bellied ever since I got them all (about 3 months ago) and thought she could be pregnant then, but nothing happened at that time and back then her scales were flush against her body like normal.

Answer
There are a couple things going on here. I should be able to help you with all of them, but we'll start with the most important issue. That would be the Guppy who's scales are popping up, looking like a pine cone. That is the age old description of Dropsy.
Dropsy is actually more of a secondary infection than an actual infection. An Internal Bacterial Infection is usually the cause of Dropsy. What are your water parameters? pH, Nitrate, Ammonia, etc? Do you have a hospital tank, if so I would recommend placing the infected guppy into the tank. There are kinds of dropsy that aren't contagious but there are still forms that aren't curable either. I wouldn't be able to tell exactly what type of Dropsy your fish has, so I would definitely put it in a separate tank if possible just to be safe. Also she needs treatment and you don't want to treat the other fish if they aren't sick. I have to be honest and say that dropsy is one the  hardest internal bacterial infections to cure. By the time the scales begin to raise it is considered almost impossible to save the fish.
Whenever you see signs of illness in your fish, check you parameters and do a thorough cleaning. Poor water quality is the biggest cause of fish illness. You can give salt baths which will help draw the fluids from the fish. Just follow the directions on the box, when treating for medical issues you can add up to but not to exceed... 3 tablespoons salt per 5 gallons of water. For medications you can use Tetracycline. Again follow the instructions on the bottle. When using medications like Tetracycline, always follow the instructions exactly as they are written. In large doses, these medications become toxic to fish :) Also, when you change the water, add some water conditioner like Stress Zyme, along with the water stabilizers it has things that will help heal and regenerate damaged tissue.
Now off to the other question :) How many males and how many female guppies are in your tank? I suggest 3 females for every one male. Otherwise the males will run the female ragged trying to breed. That is probably why she's been laying in the plant "hiding" from them.