Why is Fish Ta why does my fish tank smellnk Smell

8 Reasons Why Your Fish Tank Smell (And Steps to fix it!)

Tropical fish tanks or aquariums are a lovely addition to any home or office décor. From small kids to adults, they attract everyone. However, they are more than a decorative element of a home; they create a fantastic vibe. If you have heard of feng shui, then you probably know that the fishes can bring luck. Even the psychologist believes that if you spend time with the fish pets, they help you to release your stress overall.

Since fishes don’t leave odors all over the house like other pets, they are the most odorless pets that you can include in your life. Most fish tanks have a mild scent. However, sometimes you may encounter an unpleasant smell, especially when you are near the tank or cleaning it. Well, if you feel that your fish smells bad, it doesn’t mean it is due to fish present in the tank; it means that something is wrong with that causes your fish tank to smell.

And undoubtedly, stinking tanks are something that no one ever wants to talk about. Since the scent is in the air already and can be noticed quickly, it can embarrass you in front of your guests. Apart from this, they are unhygienic and can cause various health issues. However, you’re not alone who have faced this issue; I have been there too.

Hence, I decided to end the struggle right now. In this article, I am going to tell the real causes of why your fish tank stinks and how you can prevent it. Without wasting much time, let’s get started.


Do fish tanks have a natural smell?

An underwater ecosystem is always a fun and exciting part if you have it at home. Especially if you are setting them up on your own, it is going to be an adventure. Starting from finding the place to choosing the light to set up the tank, it will be a different experience. You can observe that there is yet another world out there.

However, before you go ahead, you need to know that there are two types of fish tanks: Freshwater and saltwater tanks.

Freshwater fish tanks:

They have a mild odor of the moist mud more like soil tilled freshly. The aroma is soothing and creates a gentle vibe.

Saltwater fish tanks:

You can feel the smell of beach sand in these tanks – a slight aroma of ocean soil. Sometimes, they have a summer lake smell.

Generally, if you have maintained the tank appropriately, the smell can be retained. But honestly, the scent fades away in a few months and can’t be sensed because of some external factors.


What smell should your fish tank have?

The answer is comprehensive. There is no fixed odor for the fish tank apart from the natural smell it carries. Usually, the scent of the tank depends on the different elements. For example, are you going to have plants? What type of fish are you bringing? What kind of filter do you use? All these elements contribute a lot to deciding the smell of your fish tank.

Commonly, the clean water tanks have the smell of wet soil that usually occurs after rain. The reason behind it is that the scent of fresh tanks is not very heavy unless you go closer to them. Secondly, they don’t possess the odor of stagnant backwater.

In case if you sense adverse odors, it is high time that you need to change the water. However, there are many other reasons for a stinking smell. Below are a few reasons why your fish tank smells.

What are the alarming signs that show it is high time to take some action?


When fish tank smells swampy

If your fish tank smells like a swamp, then there are high chances that you need to check them quickly. The bacteria are building up highly in your fish tank, which is a sign of the swampy smell. When the organic waste is stuck to the substrate, it does not allow the oxygen to circulate in the tank. The bacteria will eventually grow in the low oxygen aquatic environment, which will smell like a swamp or musty. If this goes unnoticed, then the phosphate levels in the tank increase, which will feed the bacteria and become poisonous.


When the fish tank smells mold 

The fish tank smelling mold is the sign to denote the growth of algae and fungus. People think it’s highly unlikely of how mold can grow in the aquarium environment. But these are the smell of blue-green algae growing in the tank. These blue-green algae-like substances are known as Cyanobacteria, which are the reason for causing mold smell. There are hundreds and thousands of species that look the same but possess different traits. Also, their odors are accompanied by the filmy layer on the glass. It is visible, and you can see them everywhere, like in the rocks, driftwoods, and other decoration materials.

Apart from this, you may notice some brown algae, which is known as diatoms. These typically form brown layers in the glass and are mostly odorless unless you touch them. But once you have kept a hand to clean them, it needs to be done correctly. Otherwise, they smell bad and spread to the entire room. You can use normal clothes to remove them entirely by just wiping it off.


When fish tanks are cloudy

There are two primary reasons why the tanks get the cloud. One of the major reasons behind the cloudy fish tank is unclean gravel and unfiltered dirt. When the nitrifying bacteria are spread through the water, they cause a hazy, cloudy nature in the tank itself, which may be cleared naturally. However, the unfiltered dirt will accumulate more bacteria that can lead to the odor. But the gravel needs to be chosen rightly and set strong for creating a clean atmosphere. Since they are one of the reasons for filtration to occur smoothly, they become an essential element for the tank. But if you leave the cloudiness for long, it may lead to the death of fish.

Saying all that, now you may be clear about the reason why your fish tanks smell bad. Also, the alarming factors should be noticed to avoid any distortion in the tank. Now, I will discuss how you can treat this smelling tank.


Why does a fish tank stink? Causes of Smell


1. Dead Fish

The most commonly found cause for a smelly tank is the dead fish. The odor is so strong that you can even smell it as you pass by the place. The first thing you need to do is to look out for any lifeless floating bodies. Mainly if the death of fish has occurred when you have gone for a vacation or haven’t been at home for a while, then you may find it difficult going closer to the tank.

Fishes have proteins and oils found in their bodies more than anything. So, they can easily smell outside. If you have plant-decorated tanks, you may have a tough time finding the dead fish. You have to search for it in every corner and also between the plants. If you leave them for more than a week over there, it will start decomposing in the tank itself.


2. Excess Food

One of the common mistakes people having aquariums do is to overfeed the fish. The problem is that people are unaware of how much they should feed the fish. Therefore, when the uneaten food balls settle at the bottom of the tank, they colonize and form bacteria. This bacterial growth causes bad smelling in your fish tanks.

When the tank is not maintained, the bacteria from the bottom start to release the gas, which is why you can sense the foul odor in the tank. These poisonous gases are not only causing the stench but are also very dangerous to your fish pets.

I know that you love your fish, but it does not mean you can overfeed them. It is always recommended not to overfeed your fish pets to maintain the hygiene of your fish tank and beloved pets.


3. Fish Waste

Excessive bio-waste can be one of the reasons for the stench. When the organisms in the tank eat, they produce excrement, which is natural. But when the fish tank is not cleaned regularly, and the filter is not in the right condition, they start to accumulate, which in turn, causes your fish tank to smell bad heavily.

Generally, fish waste smells more like Ammonia, which has a mild pungent odor. Since they are mixed with other waste like food waste or decaying plants, it produces a strong discernible smell. You must change the 20 or 30% of the water frequently like three days once so that the filtration is smoother. If you have big-sized fish, it is recommended to change 20% of the water daily.


4. Plants Decaying

Do you know that the plant wastes cause a horrible smell than a dead fish itself? Well, it is true. When the plants are dead and decomposing underwater, they emit nitrates. That is why your tank has a stench. But it is very easy to detect these decomposed plants than the small dead fishes.

These nitrates emitted in water for a long time can affect the eyes of the fishes. Most people assume that the decomposed plants become manure, which is good for the plants. However, what they don’t know the fact is that this is only true for the terrestrial plants, not the aquatic ones. Also, the stems are thick, and they might also block the filter holes. It will result in bad filtration. Hence, it is good to regularly check your fish tank and remove the dead decaying plants.


5. Overstocked Tank

It is the dream of every fish owner to gaze at the aquarium and wonder about the number of fishes in there. Here the problem begins as the tank does not come with the stocking chart. Many pet owners overstock the tank, and that’s a sign of the disastrous outcome.

The larger the surface area of water, the better the exchange rate of oxygen. But if you overstock your tank, not only it decreases the oxygen level, but the excreted waste will also be more. And there is no doubt that the decomposition of any waste will take time. As a result, the fish tanks start to stink quickly.

All you need to do is recalculate the dimensions of the tank, find out if it is overstocked with the rule one fish inch per gallon. Even though it is a rough estimate, most owners find it useful. Transfer the extra fish to another tank to get rid of the smell.


6. Substrates

There are times when the fish owners tend to feel that there is a rotten egg smell coming from the tank. You can easily differentiate this smell from others. The odor is coming from the substrate that could be at fault. Here substrate refers to any loose material that makes the bottom layer of your tank. They can be gravel, sand, pebbles, and even the manure balls that cover the aquarium bottom.

If you have not picked the right substrate for your tank, they tend to produce different zones in the tank with no oxygen. It does not stop there; the waste gets trapped in these zones and colonizes to form different bacterium in the same place. Later they slowly release gases, which is why the tanks start to stink badly.

Before setting the substrate, take suggestions from any experienced tank owners. Because this will depend on the fish and the tank set up itself. For instance, the planted tank may need multiple layers to support the filtration process. The Catfish tank may only need pebbles or sand only.


7. Filter

Tank filter is mandatory, regardless of its size. Whether you have only goldfish in your tank or a school of tetras, it is necessary to have the filter. All the above-said things can easily be solved if the tank filter is appropriate. When you open filters to clean, you can see the sludge, which is more than the aquarium waste itself. After all, they are the junkyard of the fish tank.

Mechanical filtration is the key to cleaning the tank with minimal effort. They can even remove the waste that cannot be seen by our naked eye. But when you are not cleaning the filters regularly or letting the gunk accumulate, then they start floating in the water, which causes a foul smell. It is also recommended to buy filters that are proportionate to the size of the tank. You cannot use the standard small filter for the huge tank that has a school of fish.


8. Water Quality 

Usually, water quality is one of the primary factors that decide how your tank smells. Especially the freshwater tank must be watered with the authentic water source. Otherwise, they do not only stink but also be a threat to the fish’s lives. Many people make a mistake by mixing both freshwater and saltwater in the aquarium. In such cases, the ions in the water do not dissolve efficiently; therefore, it makes the filter process harder. Also, the decomposition will take time rather than usual.

If you are using any conditioners for the water, always check the ingredients because the conditioners that have sulfur content stink very badly. So the potassium water conditioners can be useful, but purchasing the random product can cause damage to the water quality, resulting in an unpleasant smell.


9. Improper cleaning

Consider the water tank as the home of the aquatic organism. Just like how you will be keeping the house and environment clean, even the habitat of fish needs to be appropriately maintained. It can help in thriving to lead a healthy life. If you wanted to have a stink-free tank, always clean them properly. You need not clean the entire tank. You can remove 3/4th water of the tank, and then fill the tank with some fresh water. There is no need to make the deep clean by removing the substrate and plants.

But by proper cleaning, here I mean wipe down the corners of the tank when you take the water out. Clean the mosses that are growing over the glass before filling them with the new water. All these small things can profoundly reduce the stinking smell of the tank.

The reasons mentioned above are some of the everyday situations that any fish pet owner may face. But there are cases where the fishes have jumped out of the tank and died. Mainly this is common with comet fish, goldfish, killifish, and other similar types that tend to puddle from the water. In such cases, if their demise has gone unnoticed, and if the body is behind else at the bottom of the tank, then the stench becomes appalling day by day.

However, when you notice an awful smell even if you have cleaned your fish tank properly, it is an alarming sign that there is something wrong. Keep reading the article in order to know about some alarming signs that you should take care of if you want your fish tank to stay in proper condition.



How to remove the stinky smell from the fish tanks?

Every fish tank is unique, but there is some simple proven solution that works for all of them. You can find them in the three-step processes below.

1. Water change 

It may sound cliché, but think what the very first thing that pops in your mind when you sense a foul smell from the tank is. Right! To change the water. Most of the time, it works well. Even the unnoticed or things that cannot be seen through the naked eye are washed away easily when you change the water. There are types of water changes for the aquarium setup.

  • Daily Change Cycle: Changing the water every day by replacing only 10-20% of the old water will help in creating an odorless environment near the fish tank.
  • Partial Change Cycle: You can remove half the water from the tank and replace it with the new water. It helps in removing the dead organisms, undissolved food pellets, and other micro-particles like debris and dirt.
  • Wipe off Cycle: In this cycle, the water from the tank is completely removed. Initially, the fishes are transferred to other buckets, and then the entire water is removed with the help of a sucker. You can wipe the glasses neatly and remove all the stains caused by the algae. The unsettled wastes in the tank are also removed during this cycle.


2. Maintenance

Proper vacuuming will have a significant effect on the odor of a fish tank. It will remove all the organic waste stuck in the tank. The siphon is a useful tool to remove the zone block held by the gravels. It will remove the debris and allow the oxygen to pass through them quickly.

Also, whenever you clean your tank, do some inspection to check in between the plants and stones. The system needs to oxygenate to have a clean and fresh habitat for the aquatic organisms.

Secondly, maintain your filter appropriately. Even though sponge filters are affordable, they may not be suitable for large tanks. Therefore, pick mechanical filters for efficiency. By any chance, if you find that the filters are underperforming, then having a supplement filter helps you to maintain your tank. In this way, you don’t have to clean them daily. There are ways in which the filter needs to be cleaned. Always follow the manual to clean them properly.


3. Carbon Filter


Using Carbon Filters is the most effective method of having a stink-free tank. Their absorption capacity is high, and it can reduce the stench regularly. Even though they are small in size, they can eradicate the odor. Although you may have to change them frequently for the effective use of carbon filters. Look for the activated carbon that is suitable for your tank. Especially if you have a big tank at home, then you may need the bigger carbon filter to pull the pollutants and other odors from the tank directly.


Preventive Tips to have the Stink-free Fish Tank

  • Daily look after the tank carefully: If you find any unusual behavior or find the aquatic creatures lazy, then it’s time to take action. With the planted aquariums, commonly, they form algae quickly, and the dead plants remain in the tank. Therefore, be on a constant hunt so that you can remove these substances easily.
  • Do regular water tests: If you find the previous water has a high level of dissolved materials, then you need to switch the water from tap to RO water. Usually, RO water is pure for aquariums; therefore, in between the cycles, you can switch them once in a while back and forth.
  • Use the right food: Picking the right-sized food pellets or flakes will not cause excessive food waste in the water. However, regular water change and power filters are necessary if you never want your fish tank to smell bad. You can also have the scavenger fishes like cory or plecos, which can ideally remove the grim stuck in the substrate.

If you find something most disturbing or unusual with the tanks, you can also take some medical care.


Wrap Up

Get into the habit of maintaining the fish tanks. It will take only 15 minutes of your day. All you need to do is remove the excess food, noticeable dirt and debris, and the dead organism from the tank. In this way, you can stay connected to the fish pets and provide them with a healthy environment to live in. Never overstock the tank because they can cause multiple problems overall. Whether you get mold smell or rotten egg smell, at the end of the day, remember that it is your fish tank, and it is your responsibility to take care of the creatures living in it. With regular cleaning and maintenance, you are going to have a dreamy stink-free tank soon.

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