No! Even if you have a 1,000-gallon tank, we recommend against it. Tap water should get dechlorinated before it's added to the fish tank. Some fish hobbyists say that tap water may be safe if their tank has an aeration device. But we disagree. We say it's always better to remove the chlorine first! (Keep your fish safe! One slight water quality mistake can cause your fish to get sick. Or worse.)