Goldfish Tank cloudy was due to water pollution and the definition of aquariums water pollution means when the toxic substance in the water bodies breaks and creates the water cloudy. Toxic substances such as ammonia, nitrites, and algae will affect the health of fish. Cloudy water is harmful to the fish causing stress and reducing immunity power.

Our research found that aquarium water cloudy was mainly due to poor care and improper tank maintenance. High waste substances and high ammonia in the aquariums lead to health problems such as swim bladder disorder, stress formation, and low immunity in the fish.

In this detailed guide, You’ll know the reason goldfish tanks are cloudy and different ways to prevent and treat them. When the water gets dirty or cloudy separate the fish to another tank that was water conditioned. You can also read my detailed goldfish care guide.

Why Goldfish Tank Water Cloudy (Causes)

The main reason or cause for aquarium water being cloudy is proper maintenance and improper filtration. The water becomes cloudy when the bacteria bloom or contaminated water. When chemical or physical substances break down or decay, the water becomes cloudy.

Here are a list of Reason or causes for goldfish tank cloudy and I’ll explain each of them below.

  •  Chlorine
  •  Bacterial blossom
  •  Overfeed
  •  Inadequate Filter
  •  Crowd Tank 
  •  Alage buildup
  •  Excessive lights
  •  Poor Tank Maintenance
  •  Nutrient imbalance


The water becomes cloudy when the chlorine substance is used highly. If the chlorine substance is high in the aquariums the goldfish will be staying at the top of the tank. The Goldfish is gasping at the surface area for air and the gills beat faster than common.

When chlorine has affected a fish, the fish appears to stress and quickly will die according to the chlorine level in the water. The Goldfish will suffer from respiratory problems and suffocate for longer periods due to low breathing.

According to Research, there is no medical treatment for fish to recover from highly affected chlorine. You can take treatment for repairing the damage with chlorine. You need to separate the goldfish when you found chlorine contents in the fish tank.

Activated carbon filters can remove 95% of the chlorine from the aquariums. The filter will absorb chlorine substance from the water.

Bacterial blossom

Bacterial blossom happens when Heterotrophic bacteria increase the water becomes white cloudy. Some of the bacteria are beneficial for aquariums whereas some of them are harmful. Bacterial blossoms can happen due to various reasons such as changes in water quality, low-quality feeds and their wastes, and nutrient imbalance.

It was usually harmless for fish, but changes in the water quality will affect the health condition of goldfish. The fish will be staying at the top of the tank and gasping for air all the time due to cloudy water.

You need to change 40% of the water for reducing the bacterial population. After changing the water, you need to wait for 3 hours to see the result. Make sure to treat the new water with a water conditioner for dechlorinating.


Goldfish Tank Cloudy

Overfeeding will make the tank dirty and excessive food waste will break into toxic ammonia. The waste will encourage the growth of algae with useful nutrients.

Algae need nutrients for growth and excessive food waste will make them suddenly spread and the water turns cloudy. So you need to keep a schedule for feeding the fish and remove the excessive food waste from the tank.

Inadequate Filter System

Without a proper filtration system, the aquarium water becomes cloudy due to waste substances. The main purpose of filtration is to remove debris and waste from the aquariums and clean the water to maintain the water quality. 

If the water becomes cloudy due to inadequate filtration, the fish struggle to breathe and stay at the top. It may lead to many problems such as swim bladder disorder, stress, and breathing problems and affect the goldfish’s lifespan.

Crowd Tank 

If the aquarium gets crowded with a lot of fish then the water becomes cloudy faster due to the large quantity of waste. The goldfish poop lot of waste and it could be hard for removing and maintaining the aquarium regularly. The goldfish may affect stress due to the large quantity of fish and some aggressive tankmates may attack the goldfish.

Algae Spreading

Goldfish Tank Cloudy

Algae spreading was the main reason for aquarium water turning cloudy. The sudden growth of algae will make the fish stressed. As I already mention to you the sudden changes in the water parameters will affect the fish’s health. 

So you need to control the algae in the tank and if you notice sudden algae blooming the separate fish to another tank.

 You can keep fish like plecos, and otocinclus for reducing the spreading of algae. They will eat the algae and control the algae spreading in the tank. 

You should also need to care for the tank and provide cleaning maintenance for your aquarium for reducing the algae spreading.

Excessive lights

Goldfish Tank Cloudy

Excessive lights were the reason for the aquarium water turning cloudy. The lights will help the growth of algae and live plants. So there will be a chance for the sudden blooming of algae in the tank.

Sudden blooming of algae will make the water cloudy and fish may struggle to breathe. You may have noticed the green color algae sticking on the aquarium glasses and it was difficult to clean them.

Poor Tank Maintenance

Goldfish Tank Cloudy

The next main reason for aquarium water becoming cloudy was poor tank maintenance. If you don’t clean the aquarium water every week or when it becomes dirty, there will be a chance for the aquarium water to become too cloudy.

Poor tank maintenance will help the growth of algae and toxic ammonia in the tank. So the sudden spreading of algae will make the water cloudy. You should clean the aquarium once a month and change the water once a week.

Providing filtration in the tank will make our maintenance job easier. This was one of the main reasons that a filter is important for a tank.

Nutrient imbalance

The nutrient imbalance will be the reason for the aquarium water being cloudy. The algae need nitrogen and phosphorus to grow faster. These two nutrients will make the algae grow faster and the aquarium water turns cloudy. 

What are the preventive ways for goldfish tank cloudy

For preventing the goldfish tank from cloudy, you need to do regular water maintenance for removing the waste substances from the aquariums. And set up a proper filtration system in the aquariums from removing waste and chemical substances using chemical filtration.

Overfeeding will make the water cloudy which will affect the fish’s health. You need to reduce the feeding quantity and remove excessive waste floating in the water.

Avoid direct sunlight because it will promote the growth of algae which leads to breathing and stress problems in fishes.

Why does my fish tank water turn green so quickly?

Goldfish Tank Cloudy

The aquarium water becomes green due to several reasons. But the main reason for the aquarium getting green was due to algae spreading in the tank and poor tank maintenance.

If the aquarium water turns green then you need to suddenly separate the fish into another tank.

Sudden changes in the water parameters will affect the fish’s health and they may become stressed.

It will be difficult to breathe in the green water aquarium. So they may become stressed due to low oxygen inside the tank.

Excessive light will help the plants and algae to grow faster. So you need to keep the aquarium away from direct sunlight.

Is green water harmful to fish?

Goldfish Tank Cloudy

Green water was not harmful to some fishes, they love to stay in the green water because it was a natural environment. But there are some fish that may have problems with green water.

Some fish breeds may have breathing problems and sudden changes in the water parameters and low oxygen in the tank may affect the health of fish. You may have noticed that fish stay at the top for gasping air.

It was due to the low oxygen content in the water. You can set up a filter in your tank for removing the toxic ammonia and other debris from the aquariums and provide an air pump for efficient oxygen supply to the tank.

Now, look at the reasons for aquarium water turning green.

Best Treatment For Goldfish Tank Cloudy?

These are the best way for treating Cloudy Water in the aquarium. 

Change Water

Goldfish Tank Cloudy

If your aquarium water becomes cloudy then you need to separate the fish into another tank and change the water.

If the cloudy water stays in the tank for a long time, the algae will stick to the aquarium glass and will be difficult to remove.

For cleaning the algae, you can use QANVEE Aquarium Algae Scraper Cleaner. I have used this product for cleaning the algae that stick into the tank.

QANVEE Aquarium Algae Scraper Cleaner

  • EASY TO CLEAN: Pro Aquarium scraper with wide razor blade slides everything off your glass tank with ease,Could be used as gravel spatula with protection cover on
  • GLASS FRIENDLY: Soft and sharp blade,Won’t be able to scratch your precious glass tank
  • STRONG AND HANDY: Aluminum Magnesium Alloy long handle and ABS plastic for the head makes it strong and light weight,very handy to use

You should change the water and clean the tank and make sure green color algae was not sticking to the glass.

Use API ALGAEFIX Algae Control 16-Ounce Bottle once a week for controlling the algae spreading in the tank. It was good for controlling the algae growth.

Use only once a week because over-usage will affect the health condition of fish.

Proper Tank Maintenance

Goldfish Tank Cloudy

Proper tank maintenance is very important for reducing algae spreading. If you don’t clean the tank once a month or when it becomes dirty, the algae will start spreading.

You should clean the tank every month for removing the toxic ammonia and debris from the tank. If your aquarium gets dirty, then fish will struggle to breathe air.

You can set up a filtration system in your tank for cleaning the water. A canister filter was best for filtration because it will clean the water and provide quality fresh water to the tank after filtering.

If your tank is small, then you can use internal filters for cleaning.

Reducing Light Source

Reducing light sources will reduce the growth of algae. Excessive light is encouraging algae growth and you need to avoid direct light from the sunlight.

Many people keep the aquarium near the windows and direct sunlight will change the water temperature and help the algae to spread.

How To Stop Alage Spreading in a Tank?

Goldfish Tank Cloudy

For stopping the algae from spreading in the tank, you need to change the water once a week and clean the aquarium every month. 

Use a filter for cleaning the tank and reducing the toxic ammonia. Overfeeding also makes the algae spread faster the nutrients such as nitrogen and phosphorus will help the growth of algae.

Remove excessive food from the tank and trim the live plants. You can also put algae-eating fishes in the tank for reducing algae.

How to Maintain Aquariums from green water?

You need to clean the tank once a month and provide a filtration system to the tank. Cleaning the tank and removing the algae sticks from the aquarium glass using a scrapper.

You should check the filter cartridge for any blockage. Test the water and ensure the water parameter is good.


Now you know the reason for the aquarium water being cloudy and the solution. You can use our treatment and maintenance guide for reading the spreading of algae.


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