bloated tiger barb

Question
Hey, thanks for the advice. But unfortunately one of the other tiger barb's eyes seem to be popped out. It also swims lopsided and tends to do summersaults when the lights are turned off. Is this symptoms of pop-eye? or is it something else?
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The text above is a follow-up to ...

-----Question-----
Hi Ron,

Well I have about a 28 gallon tank with 3 tiger barbs and two algae eaters. One of the barbs seems to be twice the size of the other two. Its scales are sticking out like pine cones. It's been like this for about a week. What's wrong with it? Is there a way to make the swelling go down?

-Annabelle-
-----Answer-----
Hi Anabelle,
 The symptoms you describe are called "bloat".  There are various medicines that claim to treat bloat but once it gets to an advanced stage the odds of success are low.  

 It isn't clear what actually causes bloat.  In general, it is a series of symptoms, i.e., the fish looks bloated, scales sticking out, and these might have different causes in different cases. Many people suspect intestinal issues, others suspect poor water conditions.   

 I suggest that you do a series of partial water changes. In general, it is a good idea to change 20-25% of the water in a fish tank once a week, every week.  When you see something like bloat, I would do a 25% water change immediately and then follow it up with another in a couple of days.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>

Answer
Hi Annabelle,
 I'm sorry to hear that.  It doesn't sound good at all :(

Pop-eye is also just a symptom, not a disease per se. It is often associated with a bacteria called Hexamita but it isn't clear whether Hexamita CAUSES popeye or is just a secondary infection.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>