Will My Fish Die in Cloudy Water?

New aquarium owners are sometimes quick to fill up their brand spanking new fish tanks with water and fish, only to find out that the water has gone all cloudy and the fish end up dying.

So will your fish die in cloudy water? Cloudy water usually happens because the new fish tank was put together without proper cycling. Fish introduced to the aquarium without proper cycling often leads to an overload of ammonia, which then leads to lots of dying fish.

The key to becoming a successful fish owner is to put in place a Nitrogen Cycle which helps level off the ammonia and nitrate in the water.

Will My Fish Die in Cloudy Water?, Aquarium Fish Tanks UK

Is Cloudy Water Bad for Fish?

Cloudy water in an aquarium is a normal part of the cycling process that should happen after a water change of prior to introducing fish.

If you are a first time owner of a fish tank, then it is important to know that your tank needs to cycle through to allow the filter to be ready to handle the amount of fish waste produced. Water clarifiers are great devices to have to hand, but it is also good practice to be aware of the causes and implications of having cloudy water in your fish tank.

If you only recently introduced fish into your aquarium, or if you overloaded a new fish tank with fish after purchase, then there is a high chance that this is the likely cause of the cloudiness you are experiencing.

When you set up an aquarium without proper cycling, and then overload it with fish, the levels of ammonia the fish produce can kill them. The cloudiness is usually as a result of a bacterial bloom that was using up the ammonia in the water.

Unfortunately, the only way to get rid of this cloudiness is to allow it to run its course. The cloudiness clears up over time as the cycle runs its course.

It can sometimes take as long as four or five weeks to fully cycle an aquarium making it habitable for fish. Then water should then be monitored and tested often. As soon as the ammonia and nitrate levels drop to zero and stay at that level for at least two days, then the fish tank can be considered fully cycled.

What Causes Cloudiness In A Fish Tank

What causes cloudy water in aquariums and fish tanks has perplexed many fish keepers over the years, with some worrying if it’s just a case of low oxygen. Despite this, there is no single obvious answer as to why aquarium water becomes cloudy – because it can be due to any of a number of reasons.

On the plus side, the colour of the cloudiness and your actions in the lead up to the cloudiness in your fish tank appearing can help figure out the potential causes.


As easy as it seems putting too much food in your fish tank can cause cloudiness to occur. It is important to space out how often you attempt to feed your fish. Fish have a really small abdomen and are able to fully consume meals required in a little over sixty seconds.


Sometimes overloading a fish tank so soon after setting it up can lead to cloudiness occurring. As a rule of thumb for freshwater fish, is to keep the fish population to one-inch size of fish to each gallon of water.

Water Changes

The irony of water changes is that not changing the fish tank water enough or changing it too much can both lead to cloudy water issues. When water is not changed as frequently as it should, debris collects in the aquarium, fish waste and uneaten fish food start finding their way around in the water. Shortly. afterwards, you’re in the position where you are trying to figure out how to save your dying fish.

Where possible, about 20 % of the water volume in an aquarium needs to be changed on a weekly basis. The frequency of this only needs to increase in the event of fish tank cycling being done.

The flip side to this is excessive water changes can also lead to cloudiness in fish tanks. Removing a large amount of water from the aquarium ends up disturbing the bacteria bed. What often happens is fish tank often becomes cloudy for a couple of days until the biological filter re-settles itself.

The key to having clear water is to plan regular and small water changes.