What should I do if the water in my fish tank is cloudy?

What should I do if the water in my fish tank is cloudy?

If you have a fish tank, you know how important it is to maintain the quality of water. One of the most common problems that fish owners face is cloudy water. This can be frustrating and alarming, but don't worry! In this article, we'll explore the causes of cloudy water, the dangers it poses to your fish, and what you can do to fix it.

What is Cloudy Water?

Cloudy water in a fish tank is a result of suspended particles in the water. This is different from green water, which is caused by an overgrowth of algae. There are three main types of cloudy water:

  • Green water - Caused by an overgrowth of algae, which turns the water green.

  • Brown water - Caused by tannins released by decaying plants and driftwood.

  • White water - Caused by suspended particles in the water, which can be bacteria, parasites, or other organic matter.

What Causes Cloudy Water?

Cloudy water can be caused by a number of factors, including:

  • Overfeeding - Overfeeding your fish can lead to excess food and waste in the tank, which can cause cloudy water.

  • Overstocking - Having too many fish in the tank can cause excess waste and cloudy water.

  • Poor filtration - If your filter isn't working properly, it won't be able to remove waste and debris from the water.

  • New tank syndrome - When you first set up a new tank, it can take several weeks for the beneficial bacteria to grow and establish a healthy environment.

  • Medication - Certain medications can cause cloudiness in the water as a side effect.

  • Dead fish or plants - When a fish or plant dies in the tank, it can release toxins into the water, which can cause cloudiness.

Is Cloudy Water Harmful to Fish?

Cloudy water itself is not harmful to fish, but the underlying causes can be. For example, if the water is cloudy due to excess waste and debris, it can lead to high levels of ammonia and nitrites, which are toxic to fish. This can cause stress, illness, and even death. Additionally, if the cloudiness is caused by dead fish or plants, the toxins they release can also be harmful to your fish.

What Should I Do if the Water in My Fish Tank is Cloudy?

  • Check Your Water Parameters - Before you start treating the water, it's important to check your water parameters to make sure they're within the appropriate range. You can use a water test kit to check for pH, ammonia, nitrite, and nitrate levels. If any of these levels are off, you'll need to address the underlying issue before treating the cloudiness.

  • Perform a Water Change - The first thing you should do when you notice cloudy water is to perform a partial water change. This will help remove any excess waste and debris from the water. Be sure to use a water conditioner to remove any chlorine or chloramine from the tap water.

  • Clean Your Filter - If your filter isn't working properly, it won't be able to remove waste and debris from the water. Clean your filter according to the manufacturer's instructions, and replace any worn or damaged parts.

  • Reduce Feeding - If you're overfeeding your fish, reduce the amount of food you're giving them. Be sure to only feed them what they can eat in a few minutes, and remove any excess food from the tank.

  • Remove Dead Fish or Plants - If a fish or plant has died in the tank, remove it immediately to prevent further contamination of the water.

  • Treat with a Water Clarifier - If the cloudiness is caused by suspended particles, you can use a water clarifier to help clear the water. Water clarifiers work by clumping the particles together, making them easier to remove by your filter. Be sure to follow the instructions carefully, and only use the recommended amount for your tank size.

  • Perform Regular Maintenance - Regular maintenance is crucial to keeping your fish tank healthy and clean. This includes performing regular water changes, cleaning your filter, and monitoring your water parameters.

Comparison Table

To help you choose the best course of action for treating cloudy water in your fish tank, we've put together a comparison table of some common remedies:




Perform a water change

Quick and effective

May not address underlying issue

Clean your filter

Helps improve filtration

May not address underlying issue

Reduce feeding

Helps reduce excess waste and debris

May not address underlying issue

Remove dead fish/plants

Prevents further contamination of water

May not address underlying issue

Use a water clarifier

Helps clear suspended particles

May not be effective for all types of cloudiness


Q: How often should I perform a water change?

A: It's recommended to perform a 10-20% water change every 1-2 weeks.

Q: How do I know if my filter isn't working properly?

A: Signs of a malfunctioning filter include reduced water flow, unusual noises, and a decrease in water quality.

Q: Can I use tap water in my fish tank?

A: Yes, but be sure to use a water conditioner to remove any chlorine or chloramine, which can be harmful to your fish.

Q: Can I use bottled water in my fish tank?

A: Bottled water is not recommended for fish tanks, as it may not contain the necessary minerals and nutrients for a healthy aquarium environment.

Q: Can I add more fish to my tank if the water is cloudy?

A: No, adding more fish will only exacerbate the problem. You should address the underlying issue before adding any new fish to your tank.

Recommendations for Further Reading

If you're interested in learning more about fish tank maintenance and keeping your fish healthy, we recommend the following resources:

  • The Complete Aquarium Guide by David E. Boruchowitz

  • Aquarium Care Basics by Dr. David E. Boruchowitz

  • The Spruce Pets - Fish Tank Maintenance Guide


Cloudy water in your fish tank can be a frustrating problem, but it's important to address it promptly to ensure the health and well-being of your fish. By checking your water parameters, performing regular maintenance, and addressing any underlying issues, you can keep your fish tank clean and clear. Remember, a healthy fish tank is a happy fish tank!