Okay, here’s where it gets fun. If your tap water is nasty, bottled water saves the day. Think rusty pipes or crazy high chlorine.
Also, if you’re treating a sick fish. Sometimes, a “clean slate” of distilled water (with minerals added) helps. It’s like a detox spa for gills.
Quirky fact: Many pro aquarium breeders use RO water (reverse osmosis). That’s bottled water’s super-fancy cousin. They then add minerals like a mad scientist.
Best Bottled Water For Fish Tanks at Rita Skelley blog
The "Bubbly" Danger
Never, ever use sparkling water. The carbon dioxide is toxic to fish. It also drops the pH like a rock.
Imagine your fish in a soda. That’s basically what you’re doing. They will not appreciate the fizz. They will die.
Stick to still, boring water. Fish hate excitement.
