Hi..I'm just wondering if the fish/es should be inside the tank when a water change is being carried out?? I'm asking this because the fresh water will be probably from the tap water..And tap water contains chlorine..What should be done??

when i perform my water changes i stop the filters remove the amount of water i want to change add the declorinator then refill the tank. the o's stay in the tank all time.

The only reason you should be removing your fish from the tank is to either rehouse them or to quarantine them.

When doing a water change i take some water out, add dechlorinator to the tank and wait a few mins then refill. I dont switch my filters off

Dont forget to switch your heaters off if they are going to be exposed to air during the water change. It the heating element part (the bottom part usually) is exposed to air it will get too hot and will break (a bit like having a kettle on with no water in it)