Guppy acting wierd

[ashog]

So I got my son his first fish tank nearly 2 weeks ago. I have kept fish in the past years ago. One of the fish is gasping constantly and either stays behind a rock at the bottom or behind the filter at the top. It's tail is slightly lower at the back but I can't see any disease or anything. Any advise. The fish has been like this since we bought it. Thanks If I can upload the pictures it's the yellow tail one at the back

Are the gills inflamed and red? It may have ammonia poisoning, or it may have been ill when you bought it. Check it's not being picked on and maybe separate it if you can. But other than that there is not much you can do.

Unfortunately it died. There was no signs atall of anything I checked. Must of been I'll when I got it as it was like that from when I got it