Fish Tank Smells Bad And Is Cloudy: Potential Causes & Solutions

Aquariums are an outstanding ornamental feature and a fantastic method to discover aquatic life.

The pleasure and experience are utterly wrecked if your fish tank smells bad and is cloudy.

First-time aquarists frequently encounter significant difficulties in keeping their tanks in good condition.

This article will explain why your tank smells terrible and how to remove the foul odor. Let’s dive into it!

Reasons Why Fish Tank Smells Bad And Is Cloudy

Why is my fish tank cloudy, and how do I fix it? This question is the most common in the aquarist community.

Don’t worry if your tank is having this problem. We will list all potential causes making your aquarium stink.

Dead Fish

The swim bladder of a dead fish releases gasses, causing it to sink to the substrate of an aquarium.

When their corpse decomposes, the bacteria and microorganisms inside it create even more gasses, forcing the deceased fish to come to the water surface.

An unpleasant stench fills the aquarium due to the organism’s decomposition and closeness to the tank’s surface.

This reason explains your question: Why does my fish tank smell rotten?

Therefore, look for the deceased animal throughout your aquarium and get rid of it immediately.

Fish Waste

The number of fish feces produced in the water will determine how filthy the stream becomes.

When you don’t know how to remove fish waste from your aquarium correctly, the water will emit a terrible odor.

Additionally, the stream appears cloudy when the microscopic particles circulate throughout the stream.


Usually, people feed their fish in random amounts. It’s not the best way you should apply to feed your pets.

You must wait for your pets to complete their first bite because they often only consume a tiny amount of food.

The leftover food will continue to float until they become entirely soaked and the gas inside is wholly moved.

When the foodstuff is devoid of air, it will take up water and grow heavier. Unconsumed food is floating in little pieces at the bottom of the tank.

As a result, the water becomes tainted with a stratum of organic waste behind the ornamental elements.

Overfeeding makes the stream foul, and the microbes grow on the leftover food, making it hard for your pets to breathe.


Aquariums with too many aquatic creatures have several problems. Conflicts in the fish’s behaviors and stress might happen.

An overpopulated tank’s environment can frequently develop into a poisonous one, which can cause the stream to become hazy.

Your aquarium’s microorganisms help break down waste. The filtration system functions like the lakes’ streams, purifying and aerating the tank water.

However, there is no fresh, clean water entering your isolated aquarium.

Without your interference, the waste will be stuck in the aquarium, which causes a bad smell.

overcrowded tank


Rotting Plants

A tank usually looks fantastic with decorative plants.

They give the fish a comfortable atmosphere in the aquarium and have an attractive aesthetic.

Your pets also like the environment when it resembles their native habitat.

Thus, several aquarium owners adorn their aquariums with various aquatic plants.

Aquarium plants require certain water conditions to flourish. Some also require direct sunshine, which is impractical in some homes.

Plants that require a lot of sunshine do not thrive in a confined space for long. Thus, a large number of rotting plants eventually decay.

The rotting plants pollute the stream and give it an unpleasant smell. Further, the tiny bits float in the aquarium water, giving the appearance of cloud cover.

Your pets find it difficult to move inside the stream when its clarity drastically decreases.

The aquatic creatures will begin to die if you don’t immediately treat the water.

Dirty Filters

Each filter has a maximum limit beyond which it stops filtering water. The filter collects much dirt and microscopic debris from the poisoned liquid stream.

The filtering foam becomes layered with contaminants, making it difficult for liquid from the filtration system to flow through.

As a result, the tank receives the polluted stream without any filtering.

dirty aquarium

Dirty filters

Ways To Prevent Fish Tank From Bad Smell And Cloudy Water

How do I get rid of the smell in my fish tank? You may ask this question after figuring out the causes.

If you are a novice aquarist, the following methods will help save your fish aquarium:

Change Water Regularly

Tanks require frequent upkeep. You can remove waste and leftover food from the aquarium by adding new water with a small amount.

If you want to keep the stream in your aquarium clean, it’s best to maintain the filtration system.

Additionally, you need to clean your aquarium and completely replace the water supply every 15 or 20 days.

The amount of oxygen drastically decreases as the water becomes more contaminated.

When the oxygen level is low, your fish often swim to rise to the water surface as it’s the place with a higher oxygen amount.

Among the frequent compounds in aquariums that cause odors is ammonia. Thus, you should check the ammonia level in the aquarium water using a test kit.

aquarium in the dark

Change the water regularly

Clean The Tank’s Bottom

The waste debris typically becomes caught in the gravel or the sand. Cleaning the bottom will eliminate elements releasing foul odors in the tank.

Use the sucking water pump to drain the liquid from the aquarium. However, transfer your pets to another container first.

Move the hose slowly toward the bottom of the aquarium to suction the particles on the gravel or sand.

Use Carbon Filter

A carbon filtration system works well with contaminated and foul-smelling streams.

The active carbon will kill the unhealthy bacteria, making the tank odor-free.

Remember that you need to clean the carbon filter regularly to maintain its optimal performance.

If you want to know more about carbon filters, you can click on this video:

Use carbon filter

In A Nutshell

Your fish tank smells bad and is cloudy. Various culprits are making your aquarium water contaminated and evil-smelling.

Dead animals, waste, overfeeding, overcrowding, rotting plants, and dirty filters are the leading causes.

All of these things lead to bacteria, making the water stinking and cloudy. If you deal with this problem, try the solutions above.

Thanks for reading!