HELP!

Ok - I've been religious about water changes and changing the filter, but
one of my children's goldfish is ailing. It's tank mate seems fine.

It sits curled up like a C near the bottom of the tank. It does uncurl
itself to swim around but it is truly lethargic. It does eat and poop, but
the volume of both seems low.


I've done about a 50% water change already and plan to run to store to get
more water after the bus. I'll change the filter again then. ( I use bottled
because I have extremely hard water.)

Both fish are about 7-8 years old bought for .25 cents a piece and my
neighbor's for the first 3-4 years and have always been in this tank.

Thanks!
Cheryl