I moved this to help get a better idea of what may be happening with your
tank. When you reply to this, there will be a white box at the top of the page,
answer as many of the questions as you can. This will help us out greatly.
One additional question, do you have a air pump for your tank? Slugger is
on to something with the O2 level or water being not good. Let us know
what you come up with. If you don't have any water testing kits, take a
sample to your pet store. Most places test for free. Make sure to get
actual numbers for ammonia, nitrIte, nitrAte and ph level. Don't get OK or
good.
If you have questions, don't hesitate to ask. I asked LOTS of questions
when I first started out with fishies.