What's Going On?

[Atlantis]

I was watching my fish in my 10gal planted tank today and I noticed something out the ordinary. My Rosy Barb was acting funny. It is losing color like it is stressed out and is hanging out towards the bottom of the tank. I also noticed it has a white bulge behind it's stomach. I've attached some pictures, but they don't really show the bulge well.

My tank inhabitants are:
1 Buenos Aires Tetra
3 Rosy Barbs
1 Dwarf Gourami
1 Albino Bristlenose Pleco
1 Otocinclus

 

[whitetiger_CJ]

I would put the fish in a Q tank as not to infect the other fish if it is contiguous. It looks like a fungus to me. I would medicate the fish for fungus, and if it doesn't help, go for a parasite cure. through the food preferably, but medicating the water would do ok. could you describe the bulge? hard, soft, fuzzy, internal,?ect.
It will help to pinpoint the ailment.

 

[Atlantis]

It is white and when I look at it closely, part of it seems to be semi-transparent white. The bulge is internal and appears to be hard.

 

[Menagerie]

Answer these Qs to ensure we have as much information as possible about your ailing fish and its environment:

1~What type of fish is afflicted? In addition, please describe what is wrong with the fish to the beset of your ability (i.e. cotton like growth, bloated, etc.).
2~What are your tank parameters (ammonia, nitrites, nitrates, temp, pH)? Please give exact values.
3~ How large is the tank? How long has the tank been set up?
4~What type of filtration are you using? Please give the name and number (i.e. Fluval 304) and amount of gph if known.
5~How many fish are in the tank? What kinds of fish are they and what are there current sizes?
6~When is the last time you did a water change and vacuum the gravel? How often do you do this? How much water do you remove at a time?
7~How long have you had the fish? If the fish is new, how did you acclimate it/them?
8~Have you added anything new to the tank--decor, new dechlorinator, new substrate, etc.?