Beginner's Guide

How to Maintain Aquarium During Summer?

Aquariums are mostly kept by people to make their home or workspace look more colorful and calming. But it is much more than a glass box with fish swimming inside it.

An aquarium needs your constant care and attention. Fish can feel your presence around them and want to be treated with much care. Every time of the year, they need to be nourished with great care. Either summer or winter, your fish needs your constant attention, and they need you to maintain their environment.

The increasing warmth of the summer season can affect your fish in various ways depending upon the type of tank, number of fish present, room temperature, water quality, air conditioning of the room, etc. Just because the fish are present in water doesn’t mean that they aren’t affected by summer heat. Most people fail to provide summer care to their fish and end up losing them without even realizing what they have done wrong.

In this section, I have focused primarily on the summer season, and you will learn about maintaining your tank in the summer season. You will learn about different measures about keeping your tank cool in summer.

Why Do Aquarium Fish Die In Summer?

Before getting into the topic, we should know why it’s hard to maintain aquarium during summer, and most of our fish die in the summer season.

There is a simple but crucial science behind this. The simple science term is “increased metabolism”. In summer, when the water is warmer than usual, the metabolism process increases in every fish’s body. The food they eat break down more quickly and turn into energy. So, they remain hungry for much longer. Theirs crave for food increases in the summer season. This is not just the case with fish but with every living organism. An increase in metabolic rate is the primary answer to the question, “Why is it difficult to maintain aquarium during summer?”

You may be able to fulfill the fish’s hunger by feeding it more, but the more it will eat, the more waste is produced. This uncleaned waste or extreme hunger results in fish’s death.

Another reason behind their death is that oxygen doesn’t dissolve in warm water. Increased metabolism means your fish needs more oxygen to convert the food into energy, but oxygen doesn’t dissolve properly in warm water. So, lack of dissolved oxygen is the major fish kill in summer.

What is the Ideal Temperature Range?

The ideal tank temperature is different for each fish. Most of the tropical fish prefer 70-78 F. Coldwater fish like goldfish and koi do not require a heater and can survive a temperature as low as 60 F.

In summer, it is unsafe to use a heater even for tropical fish. For most of the aquarium fish, 80F is the maximum temperature. Some fish can withstand temperature higher than 80 F but only for a short period of time. In summer, there is a higher chance that the temperature of the tank increase than the recommended temperature, so you must take special care of the tank.

So, knowing the right temperature for your fish is essential, and maintaining that temperature is also equally important. Minor temperature fluctuations are not that disastrous, but an extreme change in temperature can easily be fatal to your fish.


How to Keep Your Aquarium Cool in Summer and Prevent Overheating?

Despite not using the heater, your aquarium might exceed 80F due to room temperature. Such high temperatures can cause stress in your fish and lead to their death. There are various measures that you can take, in order to keep your aquarium, cool in summer.

Some commonly used techniques by experienced fish-keepers including me to keep the tank cool in summer ae discussed below

Removing the Lid

Removing the lid of the tank will help with the evaporation process and help to reduce the temperature of the tank. Likewise, removing the cap can help fish breathe through the surface.

Minimizing the Use of Heater And Aquarium Light

In summer, electrical appliances like heater and light must be minimized because they provide extra unwanted heat. There not many fish that require a heater in summer. So, you can either cut off the use of a heater or reduce it to around 3 hours in the evening or night time.

Mixing Cold Tap-Water, Few Times a Day

You must check your water level regularly, and if it exceeds the level that your fish is comfortable with, then cold water can be added until the proper temperature is reached. Coldwater must be slowly poured in the tank, and the temperature reading must be taken while you add the water. Too much cold water, however, can reduce the temperature significantly, and your fish may not like it.

Placing a Fan in Front or over The Tank

Another way of reducing the tank temperature is to place a fan in front of the tank. Yes, this might seem a little odd, but it is very efficient because you are not adding anything to your tank and the fish remain entirely safe. This method is more reliable than mixing cold water in the tank.

Performing Frequent Water Change

Performing frequent water change not only helps in removing unwanted waste from your tank but also contributes to keeping the tank clean. If you change 10% of the water weekly in the winter season, then performing 15-20% water change in the summer would be appropriate.

Protecting from Direct Sunlight

In summer, the sunlight is too hot to handle. This can cause extreme algae growth in the tank and also heat up the tank water by a lot of degrees. So, protecting the tank from sunlight would be a vital measure to prevent overheating.

Using Ice Cubes To Cool Down Aquarium

Everyone who has a refrigerator has either ice cubes or cool ice water. They are widely used by may to cool down their aquarium temperature. Their good side is that they are very easy to use and available to almost everyone. You don’t even need ice cubes in many cases. Cold tap-water will do just fine by just filling up the cold water in a bottle and placing it on the tank. This is the easiest way to maintain the aquarium during summer.

But using ice cubes has a bad side too as you need to be extra careful. You should not let the temperature drop below the minimum temperature. While adding cubes, you must note the temperature after adding each cube, which can get a little difficult and messy at times. Some fish are susceptible to cold water, so haphazardly adding ice cubes can be fatal. This method of the cooling aquarium is used only for cold-water fish like goldfish and koi. The tropical fish tank must not be cooled using this technique.

Using ice cubes and cold water is quite easy. You must only use this method is the tank temperature exceeds 80F or more. You must add one cube each at a time. The temperature reading must be taken simultaneously. You should immediately stop when the proper temperature for the fish is read on the scale.

Another way is by using bottles with cold water. The bottle must be placed in the water with lead closed, and due to variation in densities, it will float. You must note the temperature reading and must remove the bottle immediately when the proper temperature is obtained.

Caring For Your Fish in Summer

To maintain the aquarium during summer is very difficult; hence providing regular care is not just enough for your fish in summer. You must always act accordingly. Like we need different food and clothes according to each season, fish also need their care accordingly.

Maintaining Oxygen Levels

In summer, the water becomes warm, and oxygen doesn’t dissolve in warm water easily. This might give your fish respiratory problems. Some of the fish like bettas have labyrinth organ to respirate in such situations. But what of those fish which don’t? For them, we must use an air pump to provide oxygen. Some of the filters have air pumps include, but some of them don’t.

Controlling Overstocking

Your fish may be able to handle overstocking in winter season up to some extent, but in the summer season, even a slight crowd can be suffocating. This is due to the low concentration of oxygen available. So, in the summer season, you must be more careful while placing fish in a tank, especially small ones.

Stop Overfeeding

It is true that due to increased metabolism, your fish needs more food than required. So, it will act hungry, although you have fed them multiple times. You can increase the feeding times from 2 to 3 in the summer. But you must ensure that you are not overfeeding the fish and remove the excess food leftover.

Checking Water Parameters Regularly and Maintaining Them

In summer, the water parameters like acidity, alkalinity, chemical contents, and hardness might frequently fluctuate due to the low concentration of oxygen, a high amount of bio-load, and frequent water change. So, you must have a complete water test kit with you and perform the test every ten days. You should always be ready to take Necessary actions if you see any massive fluctuation in the parameters.

Performing More water Change Than Usual

This is the best way to take care of your fish in summer. Doing this, you not only remove the excess bio-load but also replace the warm water with cold water, which helps to keep the tank cool. I suggest you increase the frequency of water change in the summer season than at any other time of the year.

Maintaining the Water Flow

Moving water picks up more oxygen molecules and also helps in the evaporation process. So, you must maintain the water flow in summer. You can use an internal power filter of a wavemaker to maintain water flow in your tank.


Hence maintaining the tank temperature in summer is not that hard, but your fish need to thrive. Most of the reproduction and mating takes place in the summer season, so protecting your fish from the summer wave and taking extra care of them in the summer is mandatory.

As the summer is approaching, I think reading this article has helped you become prepared for summer.


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