This morning I noticed my Albino Tiger Barb wasn't doing so well. He was letting the filter currents and air stone bubbles basically carry him around the tank. I also noticed a white patch of thin flesh on his one side. I didn't think he was going to make it and good enough when I got home just a little while ago I noticed he had passed.
I've been battling these white patches on one of my Odessa Barbs as well. It started on one side but now I'm seeing a smaller one on his other side. To add to it, his scales are now starting to stick out.
I'm attaching an image of the Tiger Barb now, I'll try to get one of the Odessa when I get home from work tonight. Any idea what this could be?
Sorry for your loss
My best guess would be either a fungus or a bacterial infection, and Dropsy.
I've also had this issue with my Tiger Barbs and Green Tiger Barbs... for a while they were dropping like flies. My issue started with inadequate filtration (I was running an Aqueon QuietFlow 30 on a 29 gallon; ultimately I found it essentially useless. There's a reason those filters are cheap).
Also, Tiger Barbs are super sensitive to nitrites. Do you test your tank water for nitrites, nitrates, and ammonia? High nitrites levels (anything > 0) can essentially make Tiger Barbs more susceptible to disease. (I have no personal experience with Odessa Barbs. I'd assume they're similar, though.)
Your first order of business should be making sure your water levels are where they should be. (Check them every day for a few days after water changes, and/or if you're medicating.)
You mentioned that one of your Odessa Barb has scales sticking out; is he bloated? It sounds to me like Dropsy. Unfortunately there isn't really a cure for that, other than keeping the water levels pretty much perfect. Some say aquarium salt can help too. In my experience, it didn't hurt. But relocate affected fish to a hospital tank rather than putting salt in your main tank.
I do have one Dropsy survivor myself, so it's not hopeless.
The white patches I've also dealt with, although it's difficult to get a conclusive diagnosis. It sounds like either fungus or 'mouth fungus' (columnaris), both of which are typically treated the same way; with an antibiotic and an antifungal. The most success I had was with Maracyn Oxy, although there's enough medications out there to make your head spin. The important things, regardless of what medication you use, is to make sure the water quality is great, and remove any carbon from your filter(s).
Sorry for the essay! Here's a few links to some resources that really helped me:
If you can ignore their shameless self-promotion, this one is awesome because it has illustrations and it's very straightforward, not complicated and confusing:
Tetra Aquarium Diseases and How to Spot Them
This one has a really good format, too. It also has actual pictures, although I didn't find them helpful as the quality is hit-or-miss. However, the text is helpful.
Aquarium Connection PDF
This one is long, but thorough. The cures suggested are a bit different from most resources, but the symptoms part(s) is quite helpful:
Diseases that affect Tropical Freshwater Fish
Again, sorry for the essay! I know from experience that Googling can be maddening and frustrating and entirely unhelpful. Hopefully some of this helps. Good luck!
