Hospital Tank

Hi all.
I noticed last night that my banded killifish appears to have come down with ich. I removed it from the tank to treat it individually. I put it in a gallon of water in an icecream pail and added coppersafe medication, per directions last night. I didn't want to treat the whole tank as it is a 75 gallon and would use quite a bit. It also has plants which the bottle says could be harmed, and a stonecat. I think I remember the person who sold it to me telling me not to use it on scaleless fish. No other fish appear to be affected at this time.
The killifish is still very active in the pail. I am just wondering how long I should keep it there. I can't really get a good look at it in the bucket to see if it is still infected or not.
A little side information. I may have triggered this a couple days ago when I changed out about 15 gallons of water. I was kind of in a hurry and didn't take as much time as I should have to match temps. Most of the water I added was probably colder than it should have been. The killifish is also the last of 3 that were collected in May of 2005. The other 2 died a couple months ago and earlier this month, so I may also just be dealing with an old weakend fish whose time is nearly up. Still I'd like to postpone the inevitable as long as I can.

The water change shouldn't have done it. My tanks in the winter sit around 64-65F and after a 50% water change with cold water sit around 58F. I've had no problems even with fish from the southern states.

Get one of these from your LFS : http://www.pets-ware...-a/ALE10516.jpg to help with looking at your fish before placing it back in gen pop.

You didn't add anything else to your tank recently?

Anyway, to answer your question. I'd keep it in there for a minimum of 2 weeks and if it looks good then take it out otherwise at least 1-2 weeks more. Try adding some non-iodized salt to the container and for one that small a teaspoon should work.

You didn't add anything else to your tank recently?

Anyway, to answer your question. I'd keep it in there for a minimum of 2 weeks and if it looks good then take it out otherwise at least 1-2 weeks more. Try adding some non-iodized salt to the container and for one that small a teaspoon should work.

Thanks for the reply,
There have been no new additions to the tank since last May. All other fish still appear fat and happy. One thing that might be worth noting though, is that I have a group of spotfin shiners in the same tank, added a the same time the killifish was. One of the females from that group would appear to have ich for about 1-2 days virtually every time she would breed which seemed to be about every 2-3 weeks. She would always get over it though and look fine again 1-2 days after getting it. I know breeding puts a lot of stress on a fish, and figured this one probably had a bit weaker immune system than normal and the breeding stress just lowered it to the point where she wasn't able to fight off infection till after breeding was over. She died last summer of apparently unrelated circumstances, but that will be the topic of another post.
Also not to beat the temperature issue to death, but I'm wondering too if I should move the hospital bucket to my basement. It is colder down there, but I think more stable temperature wise. I have a programmable thermostat in the house and let it get down to 60 while at work and about 70 while home. The basement never makes it to 70 and typically ranges from about 60 to 65 in the winter. I'm thinking a gallon of water is going to change temperature with the room a lot faster than a large aquarium.
The more I think about it, I will move it to the basement. I guess it's silly to worry about 60 degree water with this fish. If I hadn't caught it it would be under 2 feet of ice right now.
Thanks again for the advice I will try the salt too.