It will kill them. I killed our little pet frog by being lazy and using tap one day...it was filtered.

I use DC tap water and seachem Prime conditioner. The DC water does have ammonia from the chloramines, but the Prime will neutralize it long enough for it to be cleared by the biologic filter (in our aquarium it usually takes 3-4 hours for the ammonia to read zero after a water change). Some conditioners do not do this, so check your conditioner carefully. To be honest, before you add the fish you should consider running a "fishless cycle" (you can google it) with ammonia to get the water really ready. The downside of that is that the fishless cycle can take weeks. What finally worked for us was getting some material from the filter of an established healthy aquarium. Good luck! Congressional has never steered us wrong.

Add a water conditioner to the water. This is essential to remove chlorine and chloramine which are toxic to fish. I had a 75 gallon freshwater tank for many years and used tap water with this treatment. I bought several fish from Congressional Aquarium, but never heard o using distilled water for the tank.

Anonymous wrote:We are setting up a freshwater fish tank for my 5yr old son and my main goal is to make sure the poor fish don't die in the first couple weeks. Based on the advice from Congressional Aquarium, we're getting the tank up and running for a couple days before adding the fish. The Aquarium staff said that DC tap water is terrible due to the amonia in it and would kill the fish - is this true and do we really need to use spring or distilled water, as they suggested? I have read elsewhere that the water will be ok once it cycles for a while. Thanks.

Yes, it will kill the fish if you take it right out of the tap untreated. You have a few options: 1) you could go with the spring or distilled water; 2) you can go to the pet store and buy a bottle of water conditioner that neutralizes all of the bad stuff in the water; or 3) you could let the water sit but that is risky because how do you know the time frame for when the water becomes acceptable?

We are setting up a freshwater fish tank for my 5yr old son and my main goal is to make sure the poor fish don't die in the first couple weeks. Based on the advice from Congressional Aquarium, we're getting the tank up and running for a couple days before adding the fish. The Aquarium staff said that DC tap water is terrible due to the amonia in it and would kill the fish - is this true and do we really need to use spring or distilled water, as they suggested? I have read elsewhere that the water will be ok once it cycles for a while. Thanks.