Can you help figure out what is wrong with my fish?

Question
QUESTION: I'm new to the world of aquariums.  I started my 20 gallon tank on Feb. 24th, 2008.  I've had a fairly successful tank.  In my 20 gallon tank, I have 5 x-ray fish, 6 tetra neons, 4(used to have 6) green tiger barbs, 2 catfish and 3 little algae eaters...can't remember the specific name...but they are little and are non aggressive and shouldn't get to be more than an inch or so.  Anyway, about 2 months ago my first tiger barb died.  I went to the petstore and they tested my water.  Said everything was fine.  Last week I noticed another tiger barb stopped eating.  It basically starved to death...I could just see it getting skinnier and skinner.  It would hang around the top of the tank and the food would float right by it and it wouldn't eat.  It died day before yesterday.  All other fish seemed to be doing fine.  Yesterday another tiger barb has stopped eating.  It is hanging around the bottom of the tank and hasn't eaten now for two days and isn't schooling with the other tiger barbs


ANSWER: Hello!

Your tiger barbs are stressed from being in a community tank, and in too small a school.

I would bring them back to the store, or if they die, do not replace them.

Tiger barbs are not community fish like many may tell you. They need groups of at least 2 dozen, and a species only tank.

Also, your algae eaters are probably either a Siamese Algae Eater or an Otocinclus. Both are a good choice.

---------- FOLLOW-UP ----------

QUESTION: I am so disappointed that this is happening.  The green tiger barbs seemed very happy in the community tank when I had six of them.  Do you think there is any chance if I brought their number up to six again they would be fine again?  The lady at the pet store told me that green tiger barbs were not as aggressive as other tiger barbs and that they would do well in my tank.  I told her all the other fish I had before I bought them. :(  And THANK YOU for your help!

Answer
Hello!

Green tiger barbs are EXACTLY the same as normal tigers, the only difference is the color. Like if you were wearing red, and your twin was wearing blue. Everything is the same but the color.

I would bring them up to at least 10, but preferably over 20 to curb agression.

-Nick