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Top 15 Common Fish Tank Problems In Your Aquarium & How To Fix Them 



Top 15 Common Fish Tank Problems In Your Aquarium & How To Fix Them

Having an aquarium is an excellent way to bring some life and color into your home. However, with this responsibility, comes the potential for a few problems.

Fishkeeping can be challenging, but with the right information, you can overcome any obstacle that may arise.

Here are the top 15 common fish tank problems in your aquarium and how to fix them.

1. Ammonia Buildup

Ammonia buildup can occur when there is too much organic waste in your aquarium. This can also be caused when the population of the nitrifying bacteria in your tank is low or its growth has slowed down.

Ammonia is extremely bad for your aquarium as it is considered a toxic substance. It harms your fish and can damage their gills. Therefore, it might be a common problem but ignoring an ammonia spike in an aquarium is something you will regret. 

How to fix Ammonia Spike in Your Aquarium? 

To avoid this issue, perform regular water changes, add an appropriate filter to your aquarium, and avoid overfeeding your fish. These are the basic steps you can take to reduce the amount of ammonia in your tank. 

You can also add additives such as FritzZyme® 9 Saltwater Nitrifying Bacteria, to increase the levels of nitrifying bacteria in your aquarium. You can add it when setting up a new aquarium or after every cleanup of the tank. 

Lastly, be careful not to remove the beneficial bacteria while cleaning. Do not scrub things too hard and using a siphon to clean the substrate is recommended. Make sure to clean the filters in the tank water itself. If you use tap water or water from any source it might contain chlorine which will remove all the beneficial bacteria. 

2. Mineral Buildup 

Sometimes if you keenly observe, you might see white rock-like depositions in the lid or top of the aquarium. Other times there can be a lot of it that proves to be a hindrance and an eyesore.

This is the result of mineral build-up in your aquarium. As the water evaporates, it leaves behind minerals like calcium in the lid. It also occurs when filters and oxygenators splash water on the lid or other parts of the aquarium.

When the water dries up, the result is a rock-like white substance in your aquarium. 

How to fix mineral buildup in aquarium? 

Fixing mineral build-up is better done immediately as the crystals will accumulate and it will be hard to remove them.

So, to avoid mineral buildup you should raise the water of your aquarium as it will avoid the splashing of water. 

If there is already mineral buildup in your aquarium, then you should remove them by wiping them off. If they have hardened too much then you can use vinegar to wipe them off and rub off with a brush. 

3. Algae Growth in Aquarium

Algae will never leave your back when you own an aquarium. They are a part of the ecosystem of the aquarium and every aquarium will contain a certain amount of algae.

In small amounts, algae are not harmful to an aquarium. The problem arises when it starts to grow too much and accumulate in the tank.

The algae growth can be caused by excess light, poor water quality, or high levels of nutrients in the water. 

How to fix algae growth in aquarium?

The very first you can do is to address the cause of the algae growth. To prevent algae growth, reduce the amount of light your aquarium receives and avoid overfeeding your fish.

As with nutrients, algae will grow immensely in your aquarium. You can also perform water changes of about 20 to 30% every week to reduce the amount of algae 

Additionally, if there is a presence of algae in the glass or anywhere in your aquarium, you should scrape it off and leave no traces behind.

4. Green Water problems

Green aquarium water is a common problem that many aquarium owners face. It can make your tank look unappealing, and it can be harmful to the health of your fish.

Green aquarium water is caused by an excess of algae in the water. Algae can grow quickly, especially in conditions where there is a lot of light and nutrients in the water.

Overfeeding your fish or not cleaning your aquarium regularly can contribute to the buildup of nutrients and lead to algae growth. 

How to fix Green water in aquarium?

The first and easiest solution is to reduce the amount of light your aquarium receives. Algae need light to grow, so by reducing the amount of light, you can slow down the growth of algae.

Another solution is to perform regular water changes. You can perform about 20% of water change every week. This helps to remove excess nutrients and waste from your aquarium and helps to keep your water clean and healthy.

You should also clean your aquarium regularly, including the filter, substrate, and decorations, to remove any buildup of waste or debris.

5. White fuzz or fungus 

The presence of a white velvety or woolly substance in the bottom of your aquarium is a common sight.

But it is not a good sign to have those white substances. What they are is a fungus and it is commonly a result of overfeeding. 

How to fix white fungus in aquariums? 

If you have white fungus floating around, then you can remove it by using a vacuum.

Then you should proceed by feeding your fish the correct amount of food to avoid them from appearing again. 

6. White or Cloudy Aquarium water 

Every aquarist has seen their aquarium go through white or cloudy water. This is a common problem and is mostly caused by bacterial blooms.

Bacteria are present in all aquariums, and in most cases, they are beneficial. However, when there is an excess of nitrifying bacteria, it can cause the water to become cloudy.

They can rapidly multiply when there is an ammonia spike and therefore appear cloudy or white when they accumulate. Overfeeding, overcrowding, use of antibiotic medicines, and overcleaning cause this phenomenon. 

How to fix cloudy water? 

Begin with lessening the amount of food that you give your fish. Overfeeding can lead to excess waste and nutrients in the water, which can contribute to bacterial blooms and cloudy water.

Be sure to feed your fish only what they can eat in a few minutes and remove any uneaten food. If there is any leftover food, then you should remove them using a siphon. 

You can also try adding a bacterial supplement to your aquarium. These supplements contain beneficial bacteria that help to break down waste and debris in the water, reducing the amount of bacteria and cloudiness.

You can also use air stones with an air pump for oxygen supply. The bubbles which air stones produce get rid of toxic gases and the oxygen supply will help the nitrifying bacteria to process the ammonia. 

7. Red Aquarium Water

You might not have always seen red-colored aquarium water, but sometimes aquariums exhibit this color.

This is a sign that there is something wrong with your aquarium. The presence of too much iron in your tank results in red aquarium water.

If you have lots of oxygen in your water the iron reacts with it and therefore results in a stronger red color.

Moreover, the presence of iron can induce the growth of algae and brings difficulties in adjusting pH levels. 

How to fix red aquarium water? 

For this, you can get yourself Poly Filter which helps in removing iron from the water in your aquarium.

Now to get the pH levels correct, you should use peat moss which will soften your water and bring the pH to normal levels. 

Although, if the mineral content is too high in your aquarium, then you should go for reverse osmosis for it is effective.

8. Fluctuating pH levels 

Fluctuation of pH levels is a common problem that can occur in aquariums. It can be harmful to the health of your fish and other aquatic animals and can cause stress, illness, and even death.

When there is an excess of organic waste and debris in the water, it can lead to a decrease in pH levels. Also, the decomposition of organic matter in the water decreases the buffering capacity.

Conversely, when there is a lack of dissolved oxygen in the water, it can lead to an increase in pH levels.

Another cause of fluctuation of pH levels is a lack of buffering capacity in the water. Buffering capacity refers to the ability of the water to resist changes in pH levels.

If the buffering capacity is low, even a small change in the amount of acid or base in the water can cause a significant change in pH levels. 

How to fix pH fluctuations?

Water changes help with pH fluctuations. A weekly water change of about 25% improves the quality of the water.

You should also get rid of all the organic substances in the substrate of your aquarium. You can use a siphon to clean out the substrate. 

You should also exchange the old filter media and add a new and clean one. This will also help in the lessening of fluctuations of pH levels in an aquarium because it will remove organic substances.

9. Bad Smelling Aquarium 

This is probably the most common problem that every aquarium owner faces. An aquarium with a bad smell is unbearable and it is an indication of a problem with your aquarium.

It is caused by overfeeding, algae growth, and old filter media are the most common causes. 

How to fix bad smelling aquarium? 

Getting rid of the bad smell in an aquarium is simple and easy. It might take some time but it is easy. 

You should start by giving a less amount of food than usual. As overfeeding is a cause, it helps with the bad odor. You should also remove all the excess food after your fish are done eating. 

You should also prevent algae from blooming. Therefore, follow steps that prevent algae growth such as less amount of light and so on. For old filters just simply remove and replace them with a new filter media.

10. Sick Fish 

Almost every aquarium owner will go through dealing with a sick fish. There are a lot of diseases that fish can get and all of them have different methods to heal.

There are diseases such as Ich, Fin Rit, Swim bladder disease, and many more. We cannot dwell on every disease but the best thing you can do is to keep the fish in the best kind of environment. 

You should keep the stress levels of the fish low as they get vulnerable to diseases when they are stressed. Therefore, the aquarium must be kept at optimal conditions.

The temperature, pH levels, and much more need to be at the preferred conditions of the fish. Then only the fish can lead a healthy life. 

Although if they do get sick there are lot of methods which include adjusting water conditions and medical methods. But the best thing would be to contact the vet.

11. Overfeeding Fish

Overfeeding in an aquarium is a major problem. Fishes sometimes appear to be hungry even after they have had their full.

So, feeding them more will only lead to leftover food, and sometimes the fish can overeat and become sick.

Overfeeding can cause a spike in ammonia and hamper the ecosystem of your aquarium. 

How to fix overfeeding in Aquarium?

Therefore, overfeeding should be avoided at all costs.

Therefore, you should feed them the amount of food they can eat within five minutes for 2 or 3 times a day.

Just remember that you should feed them less than the amount you had been giving them.

12. Overcrowding in Aquarium

This is a problem mostly faced by beginner aquarists. They get excited about owning an aquarium and want more and more fish in their tank.

Therefore, they end up having a lot of fish in a tank and this will give rise to several problems. Having too many fishes leads to a lot of fish waste products and might cause the fish to become aggressive. 

How to fix overcrowding? 

If you have already overcrowded your tank, then the only solution is to reduce the number of fish. Therefore, you should get a new tank as soon as possible and add excess fish to the new one.

But the best thing you can do is to buy a large tank if you want more fish to avoid complications.

13. Clogged Filter

Sometimes a filter can become clogged and there can be a lot of causes for it. A clogged filter can lead to poor water quality and health problems for your fish.

A clogged filter cannot clean an aquarium efficiently and becomes the source of other problems in the aquarium. 

How to fix a clogged filter? 

If you have a clogged filter, then cleaning the filter should be done immediately. You should remove the filter and clean it.

You should also remove the filter media and replace the filter with a new one.

14. Buying the wrong equipment 

Getting the wrong equipment is a common problem. People get the incorrect equipment for their aquariums most of the time.

They will have filters that are too small for their tank or sometimes too big for their tanks. The same goes for other pieces of equipment as well. Moreover, they go for cheap equipment which performs extremely poorly. 

What to do then? 

When choosing equipment for your aquarium you should always consider the size of your aquarium.

Getting the right one for your aquarium will take your aquarium to the best ecosystem.

It will also create a good environment for your fish. Also, look for high-quality equipment as they give the best performance.

15. Temperature fluctuations

Similar to pH level fluctuations, temperature fluctuations can hamper the ecosystem and health of your fish.

Frequent changes in temperature will make your fish stressed and therefore make them vulnerable to diseases. 

How to fix temperature fluctuations? 

Avoiding temperature fluctuations is a must. First of all, get a high-quality heater that will maintain the temperature in your aquarium.

Also, maintain the temperature of water while performing water changes, as the fish will get startled by sudden water changes. 


In conclusion, owning an aquarium comes with a few challenges, but with proper care and attention, you can easily avoid and solve the common fish tank problems.

Regular water changes, appropriate filtration, proper feeding, and testing your water regularly are essential steps to maintaining a healthy environment for your fish. With a little effort, you can keep your aquarium thriving and enjoy the beauty and serenity it brings to your home. 

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