sluggish fish

Question
I have a 5 gal tank only 3 weeks old, I think I am doing everything by the book however today I have 2 platys, and 2 tiger barbs that are slugging today, and not eating. my 2 guppies are very active and eating. I did a 255 water change tonight, the ammonia was harmful. Please help!

Answer
Unfortunately, you have far too many fish in such a small tank. You will not be able to keep anything under control unless you get a bigger tank (at LEAST a 10 gallon for the fish that you have).  In a tank that small, the only thing that I would have in it is either 1 Beta fish or 2 male guppies so you can make sure they don't breed.

Your fish will eventually die if you keep them in this small tank because the ammonia levels will continue to climb.  It's like sticking 12 people in a small closet...you'd have a rough time also!

Please, I urge you to get a larger tank to facilitate your fish.  If not, like I said, you are going to wind up losing these guys.

Good luck!  ;o)