Cloudy water in an aquarium

Why does the fish tank water becomes cloudy?

This problem can be encountered by both novice aquarists and experienced fish breeders. Muddy water in a fish tank is dangerous: it makes both fish and plants sick. What to do?
First of all, you should not panic and refuse to breed fish. You can get rid of cloudy water once and for all if you approach the problem thoughtfully and seriously. Let us find out why the water ceases to be transparent.