I have been fishkeeping for many years but have never kept goldfish. A friend of mine asked for help in fish because she can't keep them alive. She loves goldfish, but was keeping them in a 5g tank (one at a time, but still not a large enough tank).

I set up a 20g tank with two filters (a biowheel and an internal filter). I used media from my established tank that has been running for around six years. She bought a fantail from Wal-Mart (I know!) but said he looked frisky and healthy.

Fast forward two days and he's very lethargic and sick looking. (I have not been there to test the water but will be going later today).

Her tap water (well water) is a bit troubling. The pH is high (8.0) and there seems to be a trace amount of ammonia in it (API test was faintly green). No nitrate or nitrate. I figured with a good biological filter and Prime to condition the water, the ammonia could be controlled, even with the high pH.

I asked her about water temp because I knew she had a heater in there (I couldn't convince her that he didn't need a heater). She said it was a bit warm last night so she took the heater out. She said the temp is lower this morning.

Any ideas? I'll post back once I'm able to get water readings. Thank you.