Fish Smell In Your Bathroom? It’s Probably This6 min read

A fish smell coming from the bathroom is very unpleasant and leaves homeowners wondering what animal may have died somewhere hidden. It’s best to find the root cause of a fish smell quickly because it can actually be a fire hazard. 

A fish smell coming from your bathroom is most often caused by an electrical fault. Light fittings and plug sockets sometimes contain urea formaldehyde which when heated causes a fishy smell. Homeowners are often surprised to hear this after checking for dead animals, clearing the sink, and cleaning the entire bathroom.  

In this article, I’m going to outline the most common causes of a fish smell in the bathroom. Even if you feel like you’ve checked every possible option, this article is for you. 

Why Does Your Bathroom Smell Like Fish?

In the next few sections, I’ll explain the very most common reason for your bathroom omitting a fish smell: overheating electrical components. 

Then I’ll move on to other, less common causes, and what you can do to remove the fish smell. 

Overheating electrical components  

Believe it or not, the most common cause of a fish smell coming from the bathroom (or anywhere in the home for that matter) is due to faulty electrics

Whilst researching this article, I found a load of blog posts where homeowners report fish smells coming from damaged electrical devices (check out this blog post with 130 comments!). 

You’ll find that the fish smell is constant despite your best cleaning efforts. This can be an absolute nightmare if you’re trying to sell your house. 

All bathrooms are different but if I take my bathroom as an example, there are a few electrical components or devices: light fixtures, GFCI outlets, an exhaust fan, an electric toothbrush charger, and a heated handrail. The picture below shows my bathroom but it makes you realise just how many electrical components you have within the bathroom: 

Electrical components within the bathroom

As electrical components overheat, the surrounding plastic material (such as within a plug socket) or wires and circuit breakers will burn. Since they are made with heat-resistant chemicals, they’ll often release a fish smell when burning.  

Plug sockets and light switches can malfunction for a few reasons but here are the most common causes: 

  • Overloading: Plugging in too many devices or devices with high power consumption can exceed the socket’s capacity, leading to overheating and socket damage. Perhaps you’ve noticed your electric shower tripping, or perhaps the opposite where it doesn’t have power.
  • Loose Connections: Poorly connected wires generate heat. Over time, this heat can build up and cause the socket to burn or melt.
  • Short Circuits: A short circuit occurs when live wires touch. The resulting high current and heat can quickly cause the socket to burn.
  • Worn Out Components: Electrical components degrade with time, becoming less efficient at managing currents and increasing the risk of overheating.
Socket Extender
Socket Extenders like this could be burning up, causing a fish smell.

If you’re observant you might start seeing a trend. Ask yourself questions like this: 

  • Is the fish smell only there when the power shower is running? 
  • Does the smell appear when the ceiling fan is on? 
  • Is the fish smell there all the time? Or just when the lights are on? 

If you suspect this to be the case, I’d recommend calling an electrician right away, especially since water and electricity are a dangerous combination. 


Another potential cause of a fish smell within the bathroom, or anywhere within the home, is due to the AC or HVAC system.

Particularly if you have a new HVAC system, it’s possible that there is mold or mildew in the system somewhere. Another potential cause would be if your HVAC system comes into contact with a condensate drain that is not draining properly, for example. As this air blows into your bathroom you might notice a smell of fish. 

It’s also possible that your AC vent is pulling in nasty odors from somewhere outside. This is probably more common in large apartment blocks where you can’t necessarily trace the root cause of where the AC draws fresh air from. 

HVAC fish smell
Look at this HVAC drawing a fish smell.

Try switching your HVAC off for a few days and monitor the smell in your bathroom. 

Lastly, it’s also possible you have a burning electrical wire or component somewhere else in the house and the AC is picking up the smell and blowing it into your bathroom. If you suspect this is the case, inspect sockets within your home for overheating and call an electrician.  

Dirty Drain

Another potential cause of a fish smell within the bathroom is dirty drains. Drains in sinks, showers, and bathtubs can become clogged with hair, soap scum, and other debris. This creates a buildup of bacteria that produces an unpleasant odor. 

I’d also recommend checking any FLOOR drains as well as sinks and tubs. Since they are used the least, they are likely to get dried up from lack of use. When they dry up, this is often when the smell starts appearing. 

Dirty Drain
Debris can easily get caught in drains.

If the fish smell is caused by a dirty drain, you’ll probably also notice that it’s slow to drain and that it gurgles every now and then. 

It’s also worth making sure your sink has a vent installed. The vent pipe can also get clogged but if this is the case you’d definitely experience strong sewer smells, a slow-to-drain sink as well as gurgling.   

Whilst you can use something like Drano (on Amazon) to clear the clog, I’d actually recommend going for a natural remedy. Drano is expensive and toxic. Instead, use baking soda and vinegar: 

  1. Ensure the sink or bathtub basin is as empty as you can make it, removing as much liquid as possible.
  2. Next, pour a quarter cup of baking soda down the drain. If it settles on the drain cap, don’t worry, this is normal.
  3. After that, take one cup of vinegar and add it to the drain SLOWLY. Be cautious not to pour too quickly to prevent excessive bubbling up and spillage from the drain.
  4. Allow this mixture to sit for about 15 minutes. During this time, it will work to break down any buildup.
  5. Once the 15 minutes are up, flush the drain with hot water. If needed, you can repeat these steps as many times as you like. 

Dry P-Trap

A P-trap is a U-shaped plumbing device commonly found under sinks, bathtubs, and showers. It traps water and prevents sewer gases from entering the building through the drain pipe.

P-Trap in bathroom
See how this P-Trap has water in it? That should always be the case.

The P-trap holds a small amount of water in its U-shaped bend. This water acts as a seal, preventing gases and odors from the sewer system from flowing back up through the drain and into the bathroom or kitchen. 

Over time, water in the P-trap can evaporate. This allows sewer gases to come up through the trap into the house. 

I have a shower in my basement which is hardly ever used, often for months at a time. As the trap dries up, it lets in sewer gas (nasty). Whilst I don’t think this smells like fish, it’s possible some other homeowners do think it’s fishy. 

If you suspect this is the case, you need to make sure the P-Traps are full of water. Flush the toilet, and run both the shower and sink for a minute. 

Mold or Mildew

Mildew or mold can grow and produce a fishy or musty odor if you have a moist bathroom. Mildew and mold are two types of fungi that can grow in damp and humid environments, such as bathrooms. 

They can cause many problems, including unsightly stains, structural damage, and health issues. One common symptom of mold and mildew growth is a musty or fishy odor in the bathroom.

Mold and mildew thrive in environments with high moisture levels, poor ventilation, and organic material to feed on, such as soap scum, hair, or other debris. If left unchecked, they can spread quickly and produce spores that can cause respiratory problems, allergies, and other health issues.

Keeping the space clean and dry is important to prevent mold and mildew growth in the bathroom. This includes wiping down surfaces regularly, cleaning the shower curtain, and using a squeegee or towel to remove excess water from the shower or tub after each use. 

It is also important to ensure the bathroom is well-ventilated by opening a window or running a fan during and after showers. If you suspect mold or mildew growth in your bathroom, it is important to address the issue promptly. 

Round Up

I’m pretty confident that if you’ve already ensured your P-Traps are functioning, cleared your drains, checked the AC as well, and checked for mold, the cause of the fishy smell in your bathroom will be caused by burning electrics. 

Whilst this probably isn’t the news you were hoping for, I hope that this article has helped you locate the root cause of the smell. 

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Hi, I'm Ed, and I run BuildFanatic! I enjoy providing the best possible information on a range of home improvement topics.

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