sophie wrote:
If none has been changed for three weeks after moving house this might
be your problem; also if you added three new fish you've doubled the
bio-load on an already overstretched system (your stocking levels are a
fair bit higher than recommended) and the filter isn't coping with the
extra waste. Did you notice vaguely cloudy white water at any point?

Basically, your water has been getting slowly more toxic over the last
three weeks. You should probably do fifty percent water changes daily
(and do use something to get rid of the chlorine) for a while and then
keep a close eye on your ammonia/nitrite/nitrate levels. If you do
intend to keep all those fish in that tank (which no-one here will
recommend, btw!) you're going to have to be absolutely religious about
water changes and you will need to under- rather than over-feed.

The white spots could be Ich, I'm not sure - you'd need someone who
knows more about stuff than me to deal with that one...

Are you serious?

The tank is nearly 3 foot long and has 6 fish in it - it looks nearly
empty!!