pop eye in tiger barb

Question
One of my tiger barbs has pop eye.  I was wondering if I maybe have too many fish.  I have a 55 gal tank.  6 tiger barbs, 2 mollys (one male one female), 1 golden mickey ( I did have 2 but one died a couple of days ago), 2 red tail sharks, 2 rainbow sharks, 1 algae eater, 6 cory fish a red crab and a snail.  Everything with the water seems okay except for the pH which had a reading of 6.0.  the pH could be lower the test only goes down to 6.0.  Since my tiger barb has gotten pop eye I changed 25% of the water, vacuumed the gravel and I brought some kind of medicine with tea tree leaves.  It is for fin rot and pop eye and the such.  Please give me whatever advice or help you can.  Thanks alot.

Answer
Hi Angela,
I dont think you are overstocked but the fish you have are not suited for that size tank. The red tail sharks and algae eater grow to 12". This means they will need a larger tank of about 70 gallons. The other fish you have are fine. Although, the ph is quite low as mollies like hard water with a little salt. Popeye can be caused by a wide range of factors including, bacterial infections, parasite infrestations, poor water quality, and internal metabolic system disorders. I would separate the infected fish to a quarantine tank. Lots of water changes and a varied diet will help him get better. There is no effective treatment for popeye. Daily water changes of about 30% may help him get better.

Good luck
Chloe.