Home Fish Why Does My Fish Tank Smell? Common Causes And Reasons

Why Does My Fish Tank Smell? Common Causes And Reasons

by Petalove
Why Does My Fish Smell Bad

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There are several possible factors for your aquarium’s odorous smell. This article is here to provide answers to one of the most common questions;  “Why does my fish tank smell?”. If your fish tank smells foul, it’s a sure sign that something went awry and needs your urgent attention.

Owning an aquatic environment should be a fun and thrilling experience that helps you to see the aquatic world from a different perspective.  Unless you put your nose directly above the tank filter, most aquariums are entirely odorless. Occasionally, however, aquarium owners record exceptionally smelly water.  If you can find a fish tank using your nose, something is wrong. Fast attention needs to be paid.

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Why Does My Fish Tank Smell: Odor Triggers

A well-maintained aquarium is unlikely to produce an overpowering odor because bad odors are typically caused by unclean biological material (bio-waste). Uneaten, aquatic rotting food, or large quantities of usual fish waste is always the culprit. But rotting plant material may be to blame. Several sources of bio-waste:

Dead fish 

The most common cause is a dead fish. It could be several days after a fish’s death before the owner knows something’s wrong. It may have hidden away from the tank corner and died, leeching proteins and oils floating to the surface and off-gas (evaporate). Promptly identifying and extracting the body will remove odor.


This is another common source of a fish tank’s unpleasant smell. Uneaten food falls to the tank’s floor, encouraging the overgrowth of bacterial colonies. As bacteria grow exponentially, they release waste gasses that smell foul.

Decomposing Plants 

Although this is less common than decomposing proteins and oils, a rotting plant can emit terrible stench when left unattended. Luckily, dead plants are quickly found. They also turn a slimy brown or black color, fouling water quality with turbid, turbid water. So if you keep lots of aquatic plants in your aquarium and are wondering why does my fish tank smell, then this could also be the cause.

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Residue Materials

A failing criterion (fish, snail, other invertebrate) caught behind part of your tank decor, a weed, or even stuck in your filter system, a dying weed or sickly creature may give off a terrible odor. 

The first thing to do is to make sure your fishy family is happy and safe. First, inspect nooks and crannies to ensure all fish are accounted for. 

Another cause of unpleasant odor stems from any plant life not adequately cared for. Sections of plants can rot underwater, leading to a residual smell. 

Finally, uneaten food that goes uneaten by the population of your tank is frequently left to rot in water and can be a third source of unwanted odors.

Causes Of Precipitation Could Be Why The Fish Tank Smells

The next set of reasons for answering the question as to “why does my fish tank smell”, is because the fish tank smells are due to water quality issues. Insufficient filter maintenance or adding excessive chemicals are two key reasons why you may smell. 

Make sure to perform regular tank maintenance that involves testing your filter system and filters, cleaning as required, and adjusting your chemical additives to avoid excessive or unwanted odors by changing around 10-15% of your tank ‘s water weekly. 

Remove water-conditioners rich in sulfur (smell like rotten eggs).

Fake Washing

Maintaining a healthy atmosphere, like your home, is part of maintaining a prosperous community. When it comes to your aquarium, you can rely on a stink-free tank while doing routine maintenance and cleaning tasks. Don’t forget to wash the tiny areas that can collect waste and bacteria for a world of healthy, smell-free water!

Treating Aquarium Water To Prevent Fish Tank From Bad Smell

If you have tried the above steps and still can’t find the solution to the question “Why does my fish tank smell”, then it may need a thorough cleaning. 

Every scent in an aquarium may be unusual, but you’ll take the same steps toward a solution. First, locate the source of the smell and remove it, then using appropriate cleaning remedies to eliminate the remaining odor.

Take your fish’s roll call to ensure everyone’s alive. When you have any fish with sickness or lethargic, figure out what’s ailing it and, when necessary, consider putting it in a quarantine tank to prevent your fish tank from smelling.

When the tank has no dead fish, move on to your live plant. Second, find and remove visible dead leaves. You ‘re also going to want to prune leaves showing some signs of weakness or those overgrown and avoid cluttering the tank. 

When the tank produces blue-green algae, physically extract them from plants and decorations. Often you can have to dust the decorations and clean them outside the tank.

Check the water for nitrate, silicate, and pH (Get API Test Kit). Too much light promotes algae production, so don’t expose your tank to too much sunlight. When using aquarium lights, keep them on for up to 12 hours per day.

Temperature And pH Maintenance

Temperature and PH can be another reason as to why your fish tank smells. Water shifts are a significant weapon in the aquarist ‘s arsenal. Although always time-consuming and unpleasant, a smelly tank has no better remedy than filling it with fresh, filtered water.

Nonetheless, major water adjustments should also be made periodically because shifting over 40% at a time can be stressful. If parameters (pH, temperature, salinity, hardness) don’t suit exactly, you ‘re triggering a significant chemistry change to occur all at once. This could also contribute to the reason as to why your fash tank smells.

Tank raised aquarium fish are versatile in chemistry. But if elevated ammonia or disease already weakens, a sudden pH change will wipe out your tank.

Since your fish is stressed due to a toxic agent in the water, I suggest using tap water conditioners like Seachem Prime containing slime coat stimulants. A healthy slime coat promotes both fish’s disease and chemical resistance.

Keep Your Tank Tidy

Get used to removing unfilled food, so it doesn’t block your filter or render your tank so filthy that you get another imbalance that results in an unhealthy water atmosphere and a sulfur smell. Adjust partial water every week or two by taking 10-20% of the water

Replace with dechlorinated drinking water. Using a long-handle scrub brush to clear it, or get an algae-eating fish like a plecostomus to help keep the tank clean. Speak to your vet about other commercially developed water additives that can quickly help you minimize potential odors.

Why Does My Fish Tank Smell: Final Thoughts

By now you should have the answers to the question of “Why does my fish tank smell”. 

There are many explanations for why your fish tank can smell bad. Dead fish, food, and polluted water are the most common factors. Luckily, they can be handled rapidly and easily with some research into their causes!

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