I don't think it is anything to worry about, your fish might have just scraped it somewhere in his tank just like we can scrap our skin. You could treat with some melafix which is meant for wounds like this. You should be able to buy it from any pet shop, just have a look around where you live and follow the instructions on the bottle.

However, if this doesn't fix it and it continues to grow than maybe it could be a cyst or tumour but I think this is unlikely. But if so the only thing you could do is to take it to a vet, a specialist one would be best and I know that they do exist and will operate on fish.

Everything else sounds great. You know something is wrong with a fish when they become lethargic and are just sitting on the bottom of their tank or are not eating. But your fish isn't showing any of this signs and I bet he just hurt himself somehow. Have a look through your tank and remove any suspicious objects.

Your fish should be fine and he is very cute

I can see it too, swollen tummy more towards the front. Follow Andreas and Nossies advice please,


but I also can see sthe else  your fishie seems to be a girl.

Common GF do have a streamlined body like our comets, only the tail is very compact

We've got both comets and commons around here But there are usually fantails, more so than any other variety actually c: Guess they're kinda' popular!

But oh, I really hope the little girl will be okay She's so cute

Thanks so much for all the comments! Glad to know she is a girl LOL She has always had a swollen belly to be honest with you. Thought  it was strange at first but as I am new to goldfish I just thought it was the way she was shaped. I have had her for six months and this is the first sign of any issues. I plan on picking up that melafix tonight after work and give that a try. I will keep you all updated on her status. Thanks again!! Oh and as far as food I feed them Aqueon Goldfish Food Flakes (its the only food I can find that doesn't contain shrimp meal and my boyfriend is highly allergic to shrimp and if I am away and he needs to feed them well he finda has to touch the food so I need to keep it safe kinda thing) Hope its a good food. Oh and I feed them twice a day, and only as much as they can eat in 2 mins. I have one other goldfish in the tank (its a 10 gallon) and a dojo loach (which are part of the goldfish community I have learned from research. I have a good filter that I clean out once a week and do a weekly 10% water change) Hope I am doing everything right 
Thanks again everyone!!

Sounds good. I will do that for sure! Thanks again

I don't know, a 10 gallon tank for 2 goldfish and a loach is awfully small!
You might want to get something bigger since loaches grow and goldfish too quite large!!
With an overcrowded tank it's hard to keep water quality in a pristine condition and then it is easier for the fish to contract a disease of some kind.  I would treat the tank with aquarium salt and melafix for now and look into a bigger set up.
You can find really nice used equiptment and tanks at yard sales, craigs list or even ebay, really inexpensive!
I've bought 2 tanks at yard sales complete set-ups and 3 on ebay!!!  They are out there you just have to look!