How long do you wait to put back your fish after using tap water dechlorinator?

Your fish can be put straight back in the tank after using dechlorinator, as long as you have not performed a whole water change. A 30% water change every 2 weeks is recommended, and putting your fish back in the tank straight after this change of dechlorinated water shouldn't do them any harm, just as it hasn't done any harm to my 3 healthy barbs (1 rosy, 2 odessas.