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Fish Tank Water Smells Earthy

Fish Tank Water Smells Earthy


If you have started noticing a strange smell every time you pass by your fish tank, you might be wondering what’s going on and how concerned you should be. It is never a good sign when your fish tank smells unpleasant!

Some freshwater tanks do have a somewhat earthy smell, and this is nothing to worry about. However, if the tank smells bad, this indicates that something has gone wrong, or possibly that a fish has died somewhere in the aquarium. Always be aware of the smell, and pay attention if it suddenly changes.

In this article, we’re going to talk about what a healthy fish tank should smell of, and what to do if your fish tank smells strange. We’ll also look at what’s normal for tanks so you know what to look out for.

Why Does My Fish Tank Smell Like Grass?

A fish tank smelling like grass is generally a good sign. If your fish tank smells grassy, it is probably healthy, and there is no need to be worried about it unless you can see other signs of problems. Healthy tanks do produce some odor, because they contain live animals, feces, plant matter, etc., and this inevitably causes a scent.

Many people find that their freshwater fish tanks have a smell a little like cut grass, and if yours smells like this, you can rest assured that it is probably operating as it should be. Some people describe the aroma as earthy, while others describe it as plant-like.

It is important to note, however, that it shouldn’t smell very strongly of grass. A slightly sweet smell of earth when you pass by or disturb the tank is nothing to be concerned about, but if you are getting a powerful aroma if you just step into the room, you should check whether anything has affected how the tank is operating.

A strong smell of any kind could signal that one of your water parameters is off, or that something is out of balance. If you notice that any strong scents, therefore, it’s worth checking the tank and doing a water test to make sure everything is healthy.

Be aware, too, that a saltwater fish tank should not smell like grass. It should smell faintly of the beach, and again, the odor shouldn’t be particularly strong.

What Should Fish Tank Water Smell Like?

A healthy fish tank should smell somewhat like fresh earth. If you have ever turned over a piece of soil and caught a whiff of the vaguely sweet smell of the soil, you’ll know what your fish tank should smell like. Think grass, soil, leaves, and a slightly damp outdoor smell.

If your fish tank doesn’t smell like this, there’s a chance that there is something wrong. You may need to inspect the tank to see if a fish has died, if you have too many algae, or if something else is going wrong. A strongly fishy scent is a sure sign that your tank is not healthy and that you need to take steps to improve things.

How Do I Get Rid Of Fish Tank Water Smell?

If your fish tank does smell bad, there are fortunately a few things that you can do to deal with this problem. One of the first is to do some cleaning. Wiping down the glass and removing and cleaning the substrate is a good start. You will need to research how to clean the specific substrate that you have.

Once you’ve done that, you should remove any dead leaves from plants in the aquarium. These will rot in the water, and this creates an unpleasant smell. Use some sharp scissors to cut off any leaves that have died and remove them from the tank entirely.

Inspect the aquarium for any deceased fish or other stock, and remove these if you find them. A rotting fish can create a really horrible smell, and this will affect the overall tank. It may also spread disease. Get rid of dead fish and make sure the remaining tank inhabitants are healthy.

Next, take out decorations and rocks from the tank and clean these too. You can scrub them with a toothbrush and disinfect them with vinegar, and then rinse them off. They can then be put back. You should also clean the inlet and outlet for the tank, and do a partial water change to increase the cleanliness.

It is also a good idea to take apart the filter and clean it out, as this is where a lot of dirt tends to get trapped. Filters need regular cleaning in order to function properly, so if you aren’t doing this, start as soon as possible. The cleaner your filter is, the cleaner the aquarium will be.

Once everything is clean and clear, you should keep doing partial water changes on a fairly frequent basis, and clean the tank whenever necessary to maintain this. The odor should soon disappear.

Is It Normal For Tank Water To Smell?

It is very normal for tank water to have some odor, yes. Aquariums will never have a neutral scent, because water, fish, plants, and algae will all produce some smell. However, this should be fairly mild, and it should not be unpleasant. If the smell doesn’t make you think of soil and the outdoors, something could be wrong.

You can use the smell of your aquarium to determine how healthy the tank is. Be on the alert for unpleasant scents, and look for signs that something is wrong. If something has changed recently, do some water tests, check for algal blooms, and see whether a fish has got stuck somewhere and died.


Your fish tank water should generally smell mildly earthy, and not unpleasant. If it smells of rotting, mold, decay, or stagnant water, there is something amiss, and you need to figure out what’s happened. Clean the tank, substrate, decorations, and filters thoroughly, and keep them clean in the following months. This should solve all problems with the smell.

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Erik Miller

Passionate scuba diver

Hello, there. Welcome to my blog. I am Erik and I’m the main editor of Sealife Planet website.

My passion and hobby has always been scuba diving. My mission is to grow this website and help others with useful information about the sea world. Enjoy! is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to

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