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Temperature in your aquarium

Temperature in your aquarium should be as constant as possible. In the natural environment of clown loaches it has about 28°C or 82°F. Still, there are only few cases in Central Europe where temperature regulation via heating or cooler for a tank with clown loaches is necessary.  

Generally one can say: even at natural circumstances temperature will never be absolutely constant, but it depends on weather and/or seasonal conditions. So a small variance in temperature is rather normal.

Most of fodder producers offer flat thermometers you can put inside the glass of your aquarium to check the temperature every once a while.


In most aquarium sets heating is included. Generally, there are two types of heating:

  1. Heater rods
  2. Floor heating

Floor heating is not visible to outsiders. Indeed I may question, in how far floor heating in a tank relates to a natural environment. Sun and heat comes from above ...

Heater rods simply hang in a corner of the aquarium.

According to my experiences, an aquarium does not need any extra heating! Even a tank that has only a short side close to a wall, can maintain a constant temperature, because lamps release heat.

My current tank is close to two walls and can maintain the temperature even in winter - when the temperature in the room is colder than in summer. This few degrees difference won't make it for the animals which are used to similar changes in nature or in their tropical home.  Generally speaking: get rid of your heating in the aquarium!

One exclusion I have to make: please mind your individual room conditions. In some flats it can be really cold, so aquarium heating is necessary!


The other way around it is also possible during a hot summer that fishes in your aquarium actually „cook“. In order to regulate the heat you have several options:

  1. Opening the tank
  2. Exchanging water
  3. Turning off light
  4. Adding ice
  5. Get yourself a cooler fan

At the first option you simply open the tank. Doing that the heat doesn’t stay inside but can move out at least. This is a quick and simple method. Depending on your fish population unfortunately it may happen that a fish jumps out of the water – this happened to me only last year! Fishes also want to escape the heat therefore that really is a danger. It was a real shock, so please keep it in mind when you use this option. Additionally, I put now grid on top of my open tank in summer.

Another option you have - and that is often practiced by a lot of aquarists during a hot summer -  is to exchange water from your tank. You would have to purchase a special hose, mostly available in do-it-yourself stores or aquarium stores. Additionally, you need a bucket. You put one end of the hose into the water and the other end into the bucket, then you shortly suck on the hose (bucketside) and let the water flow into the bucket. The size of our tank is about 400 liters; on very hot days we have to exchange five to six buckets every few hours. Exchanging means to replace hot water from the aquarium with cold water from the tap. But attention: please do not exchange too much water at a time, because bacteria and culture in the tank have to be transfered to the new water. However, using this technique you can cool your tank by a few degrees.

Addionally, you can turn off the light in the aquarium, because this also might heat up the tank - depending on the particular light-type (there were tanks without heating and light offers the only source of warmth. According to my experience the temperatures then will be warm enough even during winter); but only do this for a short time period - maybe one to three days in a row - to not have the fish in frequent dark.

In case it really gets hot in my aquarium, I often use a home remedy, so it gets cooler at least spontaniously. For this option I fill a small plastic container with water and put it into my freezer for a couple of hours. Afterwards, I throw the ice lump into the aquarium by holding the frozen container inside the water until it automatically gets loose. Fishes are curious and play with the pieces of ice swimming on the water. Having the size of your whole tank in mind in contrast to the size of the ice lump, you easily can calculate that temperature will only decrease minimally. At least, fishes can play and it helps a bit!

Another option to cool your aquarium is to use a professional cooler fan which is screwed to the edge of the aquarium. The fan uses physical effects of evaporation. You can get such a fan in different sizes for different volumina of your tank, but not more than 300 liters (at least to my knowledge there is no such tool). They will help to create a constant temperature during the hot time. Please also keep in mind – similar to an open tank – that fishes might jump out of your tank! You could  also combine the grid cover solution with the fan.

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