Fish died / cloudy tank

Ok looking for some help

One of my new fish has died (well its floating on the bottom but not moving)
its a catfish I was advised to buy to help the fish environment.

My tank is very cloudy. Only added the fish on Sunday.

Is this normal or should I be panicking? Obviously i'm very upset about the
dead catfish but the fact the water is very cloudy is worrying me as I dont
want to lose any more?

Thanks for any advice given!