First things first: you must remove the chlorine. The easiest, laziest, and most reliable way is to buy a water conditioner from any pet store. It’s a liquid that neutralizes the bad stuff in seconds.
Fill a clean bucket (a new, unsoaped bucket, please!) with tap water. Add the conditioner according to the bottle’s directions. Give it a little swirl, and voilà—your water is now safe for fish breathing. You’re basically a water wizard now.
But what if I don’t have conditioner? (Desperate times!)
You could let the water sit out for 24 hours to let chlorine evaporate, but that won’t remove chloramines. Honestly, just buy the conditioner—it costs like five bucks and saves you a world of heartache. Trust me.