One GF died tonight

At least with think it's dead, or dying. It looked fine a few hours earlier
but now it's just sitting at the bottom.

Here is the story: the kids won the two fish at a mini carnival and we
brought them home in ziplock bags. We've never had fish so we didn't have an
aquarium so we put them in the biggest bowl we had, about one gallon. After
one day I decided they needed something bigger so we bought the 2.5-gallon
"mini-bow" from Petco, but I think it's the same as shown in the link below.
We also bought one plastic plant which is supposed to glow in the dark, one
rock with holes, and some gravel. The kit comes with an under gravel filter
and some water treatment. The treatment said it was enough for 10 gallons so
I only put in about one quarter of the pouch with the tap water. There is
some Zyme stuff, too, put I didn't put it in yet. There were no real
instructions and I thought that stuff was for use later. We didn't wait very
long to put the GF in because their old home was looking pretty bleak and
never had any conditioner.

And everything looks fine for three days however there is a huge amount of
foam/bubbles at the top of the tank if you leave the pump on for many hours
so we turn it off for a few hours a day before we feed them. I don't think
it's soap. We didn't use any when we rinsed it out.

The light is probably on 2/3 of the day (I read here maybe 1/3 is better?).

The fish have been quite active the last three days until our smaller, gold
guy was found tonight just sitting at the bottom near the tube. If the
bigger white GF swims by the little guy, he get's pushed around in the wake
but then returns to a normal position after a few seconds.

My 9-year old daughter said her friend said if one fish is ill you need to
remove it so she put it in a small 1-quart bowl with tap water. She found a
nice little cardboard box to bury it tomorrow if it doesn't make it through
the night.

The white GF has been swimming around like crazy tonight, as if it really
wants out. I wonder if there is a problem with our water or ???? I keep
thinking this foam of bubbles at the top of the tank can't be good. I think
they may have been overfed, a little, but not too much. A pinch once a day,
however we have not been removing the uneaten food as recommended here I
read just a few minutes ago. I also read here the GF need a lot more room.
Sheesh. Maybe we'd be better with one yellow tang in this tank (my choice)
but my daughter would like a fish like Dori from Finding Nemo but I have now
idea how big a tank they need. We just saw them at Petco and said, those
are cool! My older daughter wants to get a huge tank and get about 10 fish
in there. Sheesh, I say, let's go slow and figure out how to take care of a
few at first and see how we do!

Thanks for taking the time to read all this. I guess I got carried away with
the details.

Here is the link to I think the same tank we have.

http://www.elmersaquarium.com/h102minibow2gal.htm