Feeding routine/ Sick fish

[miagrewal]

I have a 10 gallon tank, which is about 9 months old. I have one RTS, 2 red minnows, 2 catfish and one tetra. I have lost dozens of fish, until I started doing water changes. But the last time I did the water change, one of my red minnow started acting sick. She started to sit on the top of the ornaments I had in the tank. I have never seen my minnows sit at the bottom before. I tested the water and the temp. Everything was fine[/B]. Then I finally lost my fish. I couldn't find any marks or signs of a disease. It just looked a little pale, almost whitish. Now can U guys tell me what could have gone wrong with the water change. I put the dechlor acc. to the instructions and didn't change anything else.
My main question was,
1) I know its coming a little late but what is the appropriate way to feed the fish?? The label on the fish food containers say to feed 2-3 times a day. I feed my fish once a day. I know people who tell me they feed once every two days.
2) If I suspect that a fish is about to die, should I remove it, like mercy killing, or let it stay in the tank? I dont have a quarantine tank
3) I have two catfish, can I feed them a Hikari Algae wafer each, once a day, or would that be too much??

 

[Balloon Fish]

1)I feed once in the morning and once at night and i think most people do that too but feeding once a day is fine too.
2)Remove it asap if you know you can't treat it or else you could continue to lose more fish.
3)Feeding the catfish once a day or once every two days is fine, if it was up to me i would feed once every two days if not much of the other fish are eating it.

What are your test results? are you sure they are fine? have you cycled your tank before? and what do you mean by until i started doing water changes, do you mean you never do water changes before?? Its sort of hard to help you without some more info... oh and if you have time test the water your putting into the tank cause it sounds to me like there is something wrong with the new water.