The Best Water for Fish in a Home Aquarium

To start a home aquarium, we must choose a source of water for fish. Since fish are live animals, they are just like us requiring a clean and ideal environment to stay healthy. Unlike us, the fish are much more fragile creatures. They can die easily if we give them the wrong water.

Most people will agree on fish need clean water, but what is the definition of clean? Some people will think if the water looks clean and smells good it must be clean. The fact is that many of the chemical substances can’t be seen or even be detected by the smell. The number one fish killer in home aquariums is ammonia, followed by nitrite and chlorine/chloramine. They are all colorless, and you can’t smell them at low concentration.

Let’s get to the point.
What are the choices of water for fish?

#1 – Tap Water
In most cases, the water from your tap is the perfect choice for freshwater aquarium fish as long as you use an aquarium water conditioner with it.

Tap water is available at home to most of us, and it is the easiest and one of the cheapest sources of water you can use for home aquariums. If you are starting a freshwater aquarium, tap water will be perfectly fine unless you are certain the tap water in your area is of horrible quality.

One thing the beginner fish owners must pay attention to is that the tap water has chlorine and in some cases chloramine in it. These two substances can kill the fish.  We must and neutralize both elements before the tap water is safe to use in an aquarium. While chlorine can be easily removed by just letting the water sit for a day or two, chloramine is much more stable.  You must use an aquarium water conditioner to get rid of it.

#2 – Well Water
For some people who have access to well water, it is another choice for using in a home aquarium. However, one thing you must pay attention to is the water hardness. Due to the underground nature of the well water, it has a lot of dissolved minerals.  The minerals make the water quite hard. Although most fish can adapt to a wide range of water perimeters if given time, water hardness is one of the things the fish has the hardest time to get used to. Research well on the fish species you plan to get. If they are from soft water environment, it is advised not to use well water for them.

#3 – Lake or River Water
The water from a lake or a river is indeed a source of water. It seems natural to use it since there are fish in them. However, most aquarium hobbyists are against the use of such water. Not only you run the risk of having industrial pollution in the water, but there are also potential fish parasites and diseases of the wild.  We do not recommend this source of water.

#4 – Rainwater
Some of the people might think rainwater is clean when they live far away from the cities. The truth is that the pollution can affect a much more significant area than you think. It is not a good or even safe source of water at all for aquarium fish.

#5 – Bottled Water For Fish
If you are certain your tap water quality is horrible, the bottled drinking water is another choice. It will cost a lot more, and you will have to pay attention to the ingredient on what is in the bottled water. Some of them might not be just H2O, and they can have additives which can be deadly to the fish.

#6– Reverse Osmosis (RO) Water For Fish
The processes of creating RO water got rid of all the substances, which make it 100% pure H2O. You can obtain RO water by getting an RO unit. Some of the marine fish stores also sell RO water for reasonably low prices.

RO water is pure, which means it has absolutely nothing else in it besides H2O. It can be potentially dangerous in an aquarium where the slightest change can cause the PH to crash due to no dissolved minerals is acting as a buffer.

Important: If you decide to use RO water for a freshwater aquarium, you must add buffer back into the water before using it for an aquarium. It can be done easily by using commercially available aquarium water buffer products such as SeaChem Replenish.

The advantage of using RO water is that it is truly clean with nothing harmful in it for the fish. More importantly, you can choose your water hardness by adding a different amount of water buffer. It enables you the option to create an ideal environment for your specific fish species.

The best water for aquarium fish is tap water
While the best water of choice in term of quality and for fish health might be RO water if you are willing to take the extra cost and trouble, it does have its downside. Since you have to add buffer back into the water every time before using it, you have to make sure you rebuff the water with the same hardness every time or your fish will be in shock or even die because of the sudden change.

Tap water is the most recommended aquarium water of choice for freshwater fish. It is also cheaper than RO water. The benefits from RO water is not necessary unless you have a saltwater aquarium, or if your tap water is of terrible quality. There are other scenarios when it is a good idea to use RO water for a freshwater aquarium. It is when the tap water in your area has extreme PH (too high or too low), or when the tap water is too hard, or when there is an excessive amount of nitrate right out of the tap. Otherwise, the tap water and a bottle of aquarium water conditioner are good enough.