Why Does My Aquarium Stink

Owning an aquarium can bring joy to your home by adding a peaceful underwater world with lively fish and beautiful water plants. But if an unpleasant smell starts coming from your aquarium, it can ruin this wonderful experience. 

In this blog post, I will explain why aquariums might start smelling bad and give you practical solutions to keep your underwater paradise smelling fresh and pleasant. So, let’s begin and discover more.

The Most Common Reasons Why Does My Aquarium Stink

There are a few things that can make your fish tank smell bad. Let’s take a closer look at the most common reasons:

1. Dead Fish

When one of your fishy pals meets an untimely end, things can get pretty stinky. As the fish starts to break down, it lets out a strong and really bad smell.

This is because the fish releases a gas called ammonia, along with some other nasty gases, making the air around it almost unbearable.

2. Bad Water Quality

If the water in your aquarium isn’t clean and clear, it can start to smell really bad. This happens when stuff like ammonia, nitrites, and nitrates build up because the filter isn’t doing its job properly. All these things together make your aquarium a not-so-nice place to be.

3. Overfeeding

If you give your fish more food than they can eat, the extra food sinks to the bottom of the tank. This leftover food starts to rot and make stinky gases, making your tank smell bad. It’s like leaving old food out and having a bad smell in your kitchen.

4. Fish Waste

When your fish do their business in the water, it can make things smelly. If there’s too much waste and it’s not taken care of, it can create a yucky smell. This is because stuff like ammonia and other waste stuff builds up if you don’t clean it out.

5. Dirty Substrate

The stuff that collects at the bottom of your tank, called substrate, can get really dirty. If there’s uneaten food, poop, and old stuff that’s breaking down there, it starts to smell bad. This is because all these things together make a stink that you don’t want in your tank.

6. Plant Problem

When the plants in your aquarium start to die or rot, they let out smelly stuff. This stuff has a sulfur smell, kind of like rotten eggs. This adds to the bad smell in your tank

7. Water Conditioner

Sometimes, if you don’t use water conditioners or dechlorinators correctly, it can make your tank smell strange. These things are supposed to help your water, but if you don’t use them right, they can add a weird smell to your tank instead.

Methods to Remove Bad Smells

Image Credit: aquatic-eden.com

Now that we know why your fish tank might smell bad, let’s learn some smart ways to fix the problem.

1. Removing Dead Fish

When one of your fishy friends passes away, it’s really important to act quickly. Use a fish net to carefully take out the fish’s body from the tank. This helps prevent any extra mess or bad stuff from spreading. 

Do a partial water change. This means taking out some of the water and putting in fresh, clean water. It helps dilute any yucky things that might have been released by the deceased fish. 

These steps help keep your aquarium cleaner and safer for the other fish, and the bad smell should start to fade away.

2. Use Less Food

When it’s mealtime for your fish, it’s important not to overdo it. Just give them an amount of food that they can eat in a couple of minutes. This helps prevent any extra food from going bad and making your tank smell bad. 

By following this easy trick, you’ll keep your tank smelling nice, and your fish will stay cheerful and in good shape.

3. Remove Dead Plants

Taking care of your underwater plants is another way to keep things smelling good. Make it a habit to cut away any plants that are starting to look sick or rotten. This stops them from letting out smelly stuff. 

Check your plants regularly to see if any of them are dying or falling apart. If you spot any, take them out of the tank.

4. Replace Or Clean Your Filter

Ensuring your aquarium’s filter is well-maintained is essential for maintaining fresh and clean water. Think of it like changing batteries in a remote control; your filter’s materials, or filter media, work hard to capture dirt and grime from the water. 

Over time, they can get clogged and lose efficiency, so it’s smart to follow guidelines and replace them. Consider your filter as a cleanup crew for your tank – just as your room needs cleaning, your filter needs occasional care too. 

Regularly cleaning its parts prevents nasty buildup, keeping your tank smelling pleasant and your aquatic environment thriving.

5. Clean Your Substrate

The substrate is like the floor of your aquarium, and just like you sweep your floors to keep your house clean, you need to take care of your substrate too. 

You can do this by using a special tool called a substrate vacuum, which works like a little underwater vacuum cleaner.

It gently sucks up dirt, leftover food, and waste that can build up on the substrate. This is important because if these things stick around, they can start to create bad smells as they break down. 

By vacuuming regularly, you’re basically giving your aquarium’s floor a nice, thorough clean. And remember, a clean substrate doesn’t just make your tank look better – it also makes your fish happier and your whole aquarium smell better. 

So, show your substrate some care and attention when you’re doing your aquarium cleaning routine. 

6. Check Your Water Conditioner 

Think of a water conditioner as a special potion that keeps your fish happy. To make sure your fish tank is cozy, just follow the directions on the bottle.

Different brands have different recipes, so use the right amount for your tank. Not too little, or it won’t work, and not too much, or your tank might smell bad.

Before you pour it in, read the instructions, kind of like adding the right spice to your cooking. Using water conditioner the right way makes your fish tank safe and nice-smelling for your fish. Remember, being careful helps keep your aquarium calm and welcoming.

Tips for Maintaining A Pleasant Scent in Your Aquarium

1. Regular Water Changes

Make sure to switch out a part of the water in your fish tank on a regular basis. This makes sure the water stays nice and clean for your fish. It’s similar to when you change the water in a bathtub to keep it clean. 

This is crucial because as days pass, the water in the fish tank might start to get a little dirty and start to have a bad smell. Doing these regular water changes helps make sure the water stays fresh and cozy for your fish to happily swim in.

2. Proper Feeding Routine 

Feed your fish the right amount of food during their meals. It’s important not to give them too much food because if there’s extra food left over, it can make the water in the tank become dirty. 

Just like you don’t want leftover food sitting around in your room, fish don’t want extra food floating around in their home. So, remember to give them enough to eat, but not too much. This helps keep their living space clean and pleasant.

3. Choose Hardy Plants

Select plants for your fish tank that are tough and can handle different conditions without getting sick easily. This helps stop any bad smells from starting. Imagine having strong and healthy plants in your room – they make the air feel nice, right? 

Well, these sturdy plants in the fish tank do the same thing for the water. They make sure the water doesn’t get stinky and stays fresh for your fish to enjoy. So, when you’re picking plants, go for the strong ones.

4. Monitor Water Parameters

Keep an eye on the water in your fish tank by testing some important things like ammonia, nitrites, nitrates, and how acidic or not acidic it is. These are like the water’s health check-up.

Just like you visit the doctor to make sure you’re healthy, testing the water helps you find out if something’s not right. If these levels get too high or too low, it could make the water start to smell bad. 

So, by checking regularly, you can catch any issues early and fix them before they make the water stinky and uncomfortable for your fish. It’s like giving your fish a clean and happy home to live in.

5. Maintain Filter and Equipment

Regularly clean and follow instructions to care for your filter, heater, and other aquarium equipment. This ensures they work well and keep the water smelling pleasant.

6. Prune and Trim

Remember to trim your water plants if they start growing too big. It’s like giving them a little haircut. This helps prevent them from becoming too crowded and messy. 

When plants get too crowded, they can start to break down and make the water smelly. Just like you tidy up your room to keep it nice, trimming the plants keeps your fish’s home clean and comfy. So, give those plants a little trim when they need it.


Your aquarium should make you feel happy and calm, not like something smelly. If you learn why aquariums can smell bad and do the things we talked about in this guide, your underwater home will stay fresh and nice for you and your fishy pals. 

Taking good care of your aquarium will make it a wonderful and special part of your home that everyone loves. So, keep it clean and cozy, and you’ll have a beautiful underwater world right in your room.


Is it okay for a fish tank to smell?

No, ideally, a fish tank should not have a strong or bad smell. A slight natural odor might be okay, but if it starts to smell really bad, it could mean something is wrong with the water or the cleanliness of the tank.

How often should I clean my fish tank?

You should perform regular maintenance on your fish tank. This includes changing some of the water, cleaning the filter, and keeping an eye on the water quality.

The frequency of cleaning can vary depending on the size of your tank and the number of fish, but generally, it’s good to clean it every few weeks.

What does ammonia in a fish tank smell like?

Ammonia has a strong and unpleasant smell, similar to the smell of cleaning chemicals. If you notice a strong ammonia smell in your fish tank, it’s a sign that something is off with the water quality, and you need to take action to fix it.

Do algae eaters clean fish tanks?

Yes, algae eaters can help keep your fish tank clean from algae growth. They like to munch on algae, which can sometimes make the tank look dirty.

However, they might not be able to clean everything on their own, so you’ll still need to do regular maintenance to keep the tank in top shape.

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