KIRSTYANNE wrote:

I bought some amonia and nitrate kits and tested the water in the tank.
The ammonia levels were ok but the nitrate levels were high at 80.
When we went the our local shop they said that the nitrate level would
not harm the fish. We have also bought another bacterial remedy to try
and eradicate the problem with their cloudy/growth on their eyes.

Your local shop are idiots then. Nitrate will harm fish at high levels
and over a long period. If this was not true, what would be the point
of water changes? Try and get the levels down to 20ppm or lower, if
possible.