Aquarium care guides your fish will thank you for

Wait four to six weeks, until the tank has cycled. Fish give off ammonia, and a new filter has not yet grown the bacteria that break it down, so fish added early get poisoned. Your green light is a test kit reading 0 ppm ammonia and 0 ppm nitrite. Borrowing filter media or a cup of gravel from a running tank can cut the wait to a week or two.

Yes, once you treat it. Most tap water is dosed with chlorine or chloramine to make it safe to drink, and both burn fish gills and kill the bacteria in your filter. Add a water conditioner, sold as a dechlorinator, to every bucket before it goes in, and it neutralizes those chemicals in seconds. Get the water close to the tank's temperature while you are at it.

For a tropical tank, yes on both. The filter is where the waste-eating bacteria live, so running without one leaves the tank with no cleanup crew. The heater keeps common beginner fish like tetras, guppies and bettas in their 76 to 80 degrees Fahrenheit comfort range. Keeping goldfish instead? They tolerate a cool room, so the heater is optional, but the filter still is not.

In a tank only a few weeks old, ammonia poisoning is the usual culprit. Waste piles up faster than the young bacteria colony can clear it, and the rising ammonia burns gills until the fish give out. Test ammonia and nitrite today. Any reading over 0 ppm calls for a 25 to 50 percent water change with treated, temperature-matched water.