Why is My Betta Fish Tank Cloudy? – 9 Possible Reasons

why is my betta fish tank cloudy

One of the toughest concerns I’ve heard from newbies is “why is my betta fish tank cloudy,” the major culprits are usually the poor quality betta fish tank water, bacterial blooming, overfeeding, or a lack of oxygen.

However, these are not everything and you can discover more issues leading to this situation right below. Why not take a deeper look as soon as possible?

List Of Possible Reasons

1. Excessive lighting level


Every plant needs light, and so does algae/moss. Therefore, exposing your tank to direct light constantly may inadvertently encourage them to grow stronger and greener, making your water cloudy.

2. Overcrowding


Too many fish in a small tank brings a slew of issues within your enclosed ecosystem. Both biological and mechanical filtering systems will undoubtedly get overwhelmed by fish waste, food leftovers, and other debris. After some time, your betta tank is now full of dirt clouds.

3. Too-much and too-frequent water change


It’s obviously a must to change water for betta fish tanks but it can possibly lead to reversed problems if you overdo it, such as cloudy water or unbalanced water parameters.

Since betta fish are quite sensitive to the changing in their living area and easily get stressed, you should not neglect this issue. You should do it gradually, as changing only 25% of the water every 3 – 4 weeks is recommended.

Furthermore, please use this automatic water changer to avoid this situation.

4. Overfeeding


Because their pets constantly beg for more food, fish owners may easily overfeed their fish. As a consequence, the leftovers dissolving into water or sinking to the bottom of the tank provide an ideal habitat for bacteria to grow, resulting in a dirty tank.

5. Dirty substrates or gravel


Forget to wash the recently-bought substrates/gravels is a possible reason to make your tank get cloudy overnight.

6. Bacterial blooming


Bacterial blooming doesn’t create a cloudy fish tank after one day, it will take a few days or a week later (after setting up your fish tank). At that period, the biological filter inside the tank is developing; yet not enough to deal with all the problems at once.

This issue will also happen when you, on some occasion, turn off the filter overnight. It’s a must to have your mechanic filtration system running 24/7 if you want to keep a betta fish tank clean.

7. Phosphates and nitrates


Referring to the chemicals inside a betta aquarium, phosphates (from decomposing things/sources), and nitrates (from fish waste) can also be the culprits causing your problems.

These compounds can be found in natural plant fertilizers; therefore, algae will prefer when their concentration is higher in your tank water.

You also can use this nitrate test kit to know the nitrate concentration in your fish tank

8. Excess harmful chemicals in the water


Besides the phosphates or nitrates, heavy metals and silicates also make a betta fish cloudy water tank. To detect this problem, test your tank water’s pH level and find out whether it’s high or not.

9. Tannins


Not the tannins like you might find in wine, the tannins that can make your betta tank look dirty and cloudy come from the woody decorations.

However, besides the fact that these components can decrease the pH level in the tank water, it doesn’t harm your fish at all. They actually feel completely happy with these living condition.

Symptoms Of Cloudy Water In A Betta Tank

1. Greenish Water

Algae is definitely the main reason why your tank water looks green and cloudy. Once they are blooming, you can detect their presence everywhere in your tank, such as floating on the water surface, sticking on the substrates, or on your plants.

2. Whitish/Grayish Water

Whitish or grayish tank water, in contrast to greenish one, is a common indicator of a variety of problems with your aquarium, including overcrowding, filthy gravels, overfeeding, or an overload of dangerous chemicals.

3. Yellowish Water (Cold Tea Water Resemblance)

Lastly, move to the least common symptom and it’s when you notice that your tank water turns yellowish after a time. Don’t be panicked as it’s only because of the tannins and you can easily solve this issue.

How to Fix Those Faults And Solve This Problem?


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  • Do the water changing once a week with only 10-20% tank water each time
  • Remember to wash the new gravels/substrate under running water before putting them into your tank
  • Do not feed your fish too much. My suggestion is to give your pet fish a moderate amount of food several times a day (not a big dump at a time) and starve them once a week.
  • Prior to using the wooden decors, soak them in clean water for a few days. This process will minimize tannins (which make your betta tank seem yellow) leaching into your tank water and keep your tank water cleaner.
  • Use a decent carbon filter if you forget to do the previous tip.
  • Find a good retailer to haul these wooden tank decorations. Trust me, the good retailers will take care of all such concerns before selling their items.
  • Employ a good-quality filter for your fish tank and clean it frequently.
  • Use flocculates as an excellent ally for your mechanic filter. This chemical binds debris and particles together, allowing the machine to clean the tank more efficiently.
  • Use additional biological filters (beneficial bacteria, etc.) to balance your betta tank water condition
  • Try not to put too much fish into your betta tank. “1 inch of fish in every gallon of water” is the top 1 thing to notice before stocking fish into your tank. Don’t trust any depictions of the siamese fighting fish bowl with bettas living in a tiny space, they actually harm the poor fish.
  • Vacuum the substrate in the newly-settled betta fish tank once every week.
  • Ensure to light your tank adequately only (avoid direct sunlight or overlighting)
  • Leave your betta aquarium alone. Instead of attempting to address your issues with strong yet harmful chemicals or other fast fixes, you should choose to wait and things will eventually recover.


Overall, It’s critical to know exactly which are the main causes because it might be a more serious issue that requires you to handle it ASAP. Therefore, whenever your betta fish tank gets dirty fast, refer to my tips and fix it right away!

Frequently Asked Questions


How do you clear up cloudy water in a betta fish tank?

Beside changing the water every week, you should also employ several given tips above to clear up the dirty water. Vacuuming the substrates or using flocculates can both help your tank just as clean as the cloudy fish tank after water change.

Will a cloudy fish tank fix itself?

It depends. Although some betta fish tank problems are daunting to be solved, some can easily become better after time.

For instance, if your tank turns slightly yellow because of the tannins, it’s possible to leave it as is and it will surely get back to normal.

Why is my fish tank cloudy after 1 day?

The main causes might be overstocking or overfeeding in case your fish tank gets cloudy fast like that. Refer to my suggestions above and follow them to clear cloudy betta water promptly and efficiently.

How long does it take for a cloudy fish tank to clear?

It is decided by the issues at hand. For example, if bacteria blooming is causing your tank to get foggy, your cloudy fish tank after one day (or two) will automatically be cleansed.


Your beloved betta fish tank gets dirty fast or even gets cloudy overnight? Not your concern from now on! Hope that I have stated all the useful information for you to solve your own question of ” why is my betta fish tank cloudy”.

However, if you have any better suggestions for me, feel free to leave your comment right below. Thanks a lot in advance.