fishes loosing their eyes

i think u suggest me 70-78 degree f temp.............but as per as my experience below 26 degree celcius (80 f) my gold fishes feels sick also .........i had already ordered a test kit ..it will take 15 days of shippment......also..as i can see one of the gold fish with rashes is not well ...will it be correct decision to change the water.............should i use some medicine.........

 

The temperature of 78 f was more of a general recommendation, not that its the whole reason your fish are sick.

I would think it would be best to do the water change.

As for medicine, I would becareful sometimes it can kill the good bacteria in the filter, and cause the tank to be worse off killing the fish. You need to be sure you have a disease and not just very sick fish from bad water.

Red rashes point to bad water,
I don't know about the eye loss, is the eye cloudy or abnormally large?

 

I would try doing water changes daily for at least 3 days, as it sounds like you have ammonia problems. Add a tap water conditioner such as Amquel + (neutralizes the Chlorine and/or Chloramines if they are present as well as detoxifies Ammonia, Nitrites, and Nitrates) to the new water. I would still do the water changes even if using the Amquel + (label says you don't need to do water changes with the use of the product).

Here's a link to Amquel plus just in case you don't know what it is:

Kordon LLC - Kordon - AmQuel+