To get rid of smell in your fish tank you must identify the root cause of this and once you take appropriate action you’ll get results faster. There are primarily four reasons why your fish tank water has bad odor.
All bad smelling fish tank water is because of decaying of unwanted material such as
- Dead fish
- Dead plants
- Uneaten food
- Solid waste (poop)
Let’s have a look at these once my one so that you get a clear idea as to what needs to be done to remove bad smell.
Table of Contents
1) Dead fish –
Fish end their life in a fish tank occasionally and if it’s a community tank then it can take some time for the owner to really find out that a tank mate is dead. This situation becomes even more difficult if you have a forest of live plants grown inside the tank.
Dead body’s tiny fish sometimes get stuck in plants and go unnoticed for days and even weeks. In such conditions their body gets rotten and stinks heavily. Some other areas where you should look for dead fish, is behind decorating items, stone caves and even gravel.
The only way to avoid this is to prevent fish from dying which means create an environment where fish stay happy and grow healthy. Sometimes fish fight for life and go under stress. This stress can lead to death as well.
When fish are under extreme stress they may try to jump out of the fish tank. In such cases of you are getting bad smell from the fish tank room look for surrounding areas for dead body of the fish and get it removed.
When fish die their body either gets settled down in plants, gravel, decorations or behind stone caves etc or floats on the top surface of the tank. Always keep a habit of maintaining and observing your tank for all the fish and their behavior so that such accidents can be avoided.
2) Dead plants –
Like fish, even plants die for one or the other reason and start decaying inside the tank, the bad smell coming from rotten and dead plants will not be as bad as that coming from a decaying dead body of a fish.
When you smell bad odor start looking inside tank one by one for dead fish and then immediately look for dead plant. You may see some portion of the plant has started to become dead and the rest of the plants look good. Whichever is the case always remove either the entire dead plant or prune the dead portion of the plant from the tank.
To prevent death of plants in the tank always maintain three things that are required for a planted tank.
- Adequate light – This can be provided by fixing artificial LED lights on top of the tank
- Nutrients – These can be provided through substrate
- Pressurized Carbon Dioxide (CO2) – This is not mandatory but will definitely encourage faster growth of your aquatic plants.
3) Uneaten food –
Out of all the reason for bad smell in a fish tank, this is the most common one because this involves practice and a judgment to be made. If you make a mistake in this then most probably you’ll land up having a smelly fish tank sooner or later.
Always feed your fish only that much food that they will consume in 5 minutes of less. Fish never eat all the food you feed them and the uneaten food gets settled at the bottom of the tank. These uneaten particles immediately start decaying releasing nasty smell.
A strict cleaning schedule must be followed by the owner of the tank and during this cleaning all the uneaten food particles and other solid waste must be sucked out from the gravel and rocks using a siphon tube. This will prevent decaying uneaten particles because there won’t be left any at the bottom of the tank.
4) Solid waste (poop) –
Fish eat food everyday and produce solid waste (poop) everyday that gets dropped at bottom of the tank and starts decaying. The decay process converts this sold waste into ammonia, and other harmful gases. These gases when become excess makes your water smell really bad.
The best way to get less solid waste in your tank is to avoid having too many fish in your fish tank. The less number of fish present in your tank and less amount of solid water will get dropped. Also maintain the quantity of food you feed every day.
To prevent these situations always maintain your tank by replacing 20-25% water per week and remove dead and solid particles from the bottom of the tank using a siphon tube.
Some other reasons for smelly fish tank water
1) Faulty filter – When the aquarium filter is faulty or not maintained then the filer media will hold solid waste in it for weeks or even months causing unnecessary decay of material.
Most mechanical filters will have media that catches solid particles such as floating material, solid waste, dead material and if not removed frequently will start o decay releasing nasty odor. To avoid such conditions it is necessary that you rinse filter media in a bucket and reuse during your weekly schedules maintenance of the tank.
Never rinse the filter media in a kitchen sink or in the bathroom because most of the times there are beneficial bacteria present on the media that are responsible for converting harmful gases into beneficial ones when fish tank water passes over the media.
If you rinse the whole water into sink then there is a possibility that these bacteria also get washed off creating a huge imbalance in the fish tank environment when you reinstall the filter. Because of this imbalance there could a big spike in ammonia levels causing death of fish.
The point here to make is just like your regular fish tank maintenance of your filter also needs some servicing to avoid clogging and preventing dead material remaining for decay in the filter media.
2) Fish tank medications – Fish tank medications is another source of bad smell in your fish tank. Medications need not be always for treating diseased fish but sometimes solutions such as de-chlorinating agents etc could be added to water and these will tend to give out bad smell.
However bad odor occurring because of such type of medications or treatment will normally not last longer and is not harmful for fish as well as humans around. It id advisable that if you wish to use medications for fish disease then first shift your sick fish in a quarantine tank and then treat him there. Certain types of medications reduce oxygen levels in the main tank causing problem to all the fish.
3) Tightly packed substrate at the bottom – This one area of the fish tank is normally ignored by many fish tank owners especially when they are new to fish keeping. There are pockets in the gravel bed that get very tightly packed and oxygen does not reach in those areas. In such cases decaying and rotten material quickly releases bad odor.
When solid waste gets trapped in such tightly packed gravel bacteria convert it into gases that may smell like rotten eggs. The solution to this could be shuffling of gravel during weekly maintenance of cleaning so that no tight packets of gravel are formed where oxygen cannot reach.
4) Tap water itself is smelly – Always check the water you are storing for putting in your tank is smelly or not. This is not happen frequently but the water you receive in your tap from the city local authorities undergo a lot of treatment before you receive it in your tap and this can cause smells. Most of the times chlorine is added to water before sending out to water supply network in the city to protect from microbes and other diseases.
It’s always better to store tap water in a bucket for at least 24 hours before you put it in your fish tank.
How to prevent formation of bad smell in fish tank?
The only way to bad smell coming from fish tank water is to strictly follow a weekly maintenance schedule of your fish tank. By following such a schedule and weekly tasks you will ensure that nothing is left in your fish tank for decaying and causing smelly water.
Maintenance includes many tasks that are not at all difficult and requires a small amount of time. Some of the weekly tasks could be
- Testing water using water testing kit and checking levels of dissolved harmful gases (if any)
- Replacing 20-25% water every week using a siphon tube. This tube is also used to shuffle the gravel a little and suck out any dead plants or material beneath the gravel bed.
- Checking proper functioning of all the necessary installed equipment such as filter, heater, air pumps, lighting fixtures (if any) etc.
- If you have a planted tank then checks if the plants are healthy and growing evenly in all sides.
- Check if all the fish are alive and their movement are natural.
Does replacing water eliminate bad odor?
Simply replacing water in your fish tank will not eliminate bad odor. Unless you remove the root cause of bad smell in a fish tank simply making water changes is not going to help.
Once you remove the root cause of bad smell (as mentioned above) you will have to make water changes as part of the schedules maintenance of the fish tank. During this process the water that is giving out bad smell because of the dissolved harmful gases will get replaced and you’ll see a noticeable difference in your quality of the environment.
We talked a lot about bad smell and odors but apart from this a normal tank with all the parameters and water chemistry intact you’ll still get smell from your tank.
What should a normal fish tank smell like?
A normal fish tank should smell like earth soil and nothing else. If you maintained and follow a strict cleaning schedule for your fish tank with proper installation of all necessary equipment then your fish tank will smell much pleasant like mud in the countryside. This smell is quite friendly and not annoying at all.