white spot on tiger barb

Question
I have a 30 gallon tank, with 2 tiger barbs, 4 rosie barbs, and 1 green barb. One of the tiger barbs had a white looking spot on his tail fins, maybe from fin nipping, but now he has a white spot on his side bigger than a grain of salt, smaller than a pencil eraser. What could this be? Help!

Answer
Debbie,
It sounds like a sort of fungus, or maybe even anchor worm.
You could try a combination of Melafix and Pimafix, both are all natural and won't deplete your beneficial bacteria. Together these two medicines create a sort of remedy-all. They will also add slime coats to help your fish deal with stress.
They may have this problem due to poor water quality. Do you test the water weekly? If not, you might consider starting. Some pet stores (like Petsmart) will do water tests for you for free, and they can even help you fix your problem.
If your ammonia tests high, it means you don't have enough beneficial bacteria to cover all of your fish, and you may need to add bacteria supplement after doing a 1/3rd water change.
If your nitrates/nitrites are high, it's way past due for a water change. You should be doing at least 10% weekly.
If your pH is high, this can be solved usually by doing some good old gravel vacuuming. Just remember when gravel vacuuming it's best to do one half of the tank, wait one week, then do the other half. Beneficial bacteria lives in your gravel (among other places) and you don't want to kill it all off!
If you are able to treat this quickly then your fish should be fine. If you have a separate sick tank you should remove the tiger barb into it to reduce the risk of your other fish getting sick as well.
Best of wishes.