Do Endler Guppies Need A Heater? (Answered)

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I have been keeping and breeding Endler guppies for over 20 years and I currently keep a number of different color strains. One question I am often asked is ‘Do Endlers need a heater?’.

Endler guppies come from tropical climates and as such, they need their aquarium water to be maintained between 72°F and 82°F (22°C and 28°C). Unless the ambient temperature of the room their aquarium is in remains in that temperature region, then they will need a heater in their aquarium.

Endler guppies are seriously underrated in the freshwater fish-keeping hobby. For some reason, they are not as popular as their better-known cousin, the guppy. Endler guppies are hardy, colorful, and easy-going. They make a great addition to any community aquarium.

Why Do Endler Guppies Need A Heater?

Endler guppies originate from northern South America. The water in their natural environment is usually somewhere between 68°F and 75°F (20°C and 24°C).

However, the vast majority of Endlers we see in the hobby haven’t come from the wild. In fact, it has probably been many, many generations since the fish you have in your aquarium were in the wild. The majority of Endler guppies we buy in our local fish stores have been bred in Florida, Thailand, or Israel. They have been bred in warm water, usually between 72°F and 82°F (22°C and 28°C).

I keep my Endler guppies at about 75°F (24°C). This seems to be an ideal temperature for Endler guppies. They are active, they feed well and they breed A LOT!

What Size Aquarium Heater Do Endler Guppies Need?

The size heater an Endler Guppy tank needs will depend on the size of the aquarium and also how cold the location of the tank is. Aquarium heaters are only designed to raise the water temperature a few degrees above the ambient room temperature.

As a general rule of thumb, 5 watts of heater are required for every gallon (4 liters).

Tank VolumeHeater Size
5 Gallons (20 liters)25 Watts
10 Gallons (40 liters)50 Watts
20 Gallons (80 liters)100 Watts
25 Gallons (100 liters)125 Watts
40 Gallons (160 liters)200 Watts
50 Gallons (190 liters)2 x 125 Watts
65 Gallons (250 liters)2 x 200 Watts
75 Gallons (285 liters)2 x 300 Watts

Are There Any Circumstances Endlers Do Not Need A Heater?

In reality, the only reason any tropical fish needs a heater in their aquarium is to raise the water temperature above the ambient air temperature. Most of us keep our aquariums in our homes, but we don’t keep our homes at 75°F or higher.

If you live in an area where the ambient temperature of your rooms is a constant 72°F to 82°F (22°C to 28°C) you won’t need a heater, otherwise, you will.

There are plenty of reports of people keeping Endlers in unheated tanks where the water is only 65°F (18°C). These people will tell you their Endlers are ‘surviving’! Surviving is the keyword.

As humans, we can survive in temperatures as low as 40°F (5°C), but we want to do more than survive, we want to thrive. To do that, we need our temperature to be a little warmer, as do Endler Guppies.

How Does Water Temperature Affect Endler Guppies?

Enders can be kept at a lower temperature for a short period of time. If their aquarium water drops to 65°F (18°C) for a short period, say because the heater fails, the Endlers probably won’t notice.

I have had occasions in the past when my room heater failed and the temperature in all my tanks dropped. Most fish can shrug off a short spell at a lower temperature.

After a few days of living at a lower temperature, the Endlers’ metabolism will start to slow down. A slower than normal metabolism means the Endlers won’t grow as quickly as they should and any babies developing inside the females may not grow as they should.

Low water temperatures can also cause your Endelers to become stressed. Stressed Endlers can be susceptible to both pests and diseases. Ich (whitespot) is a classic disease that takes advantage of stressed fish.

Can Endlers Be Too Warm?

Yes, Endler guppies can be too warm. If you are keeping Endlers with some of the real warm water fish like Discus or Rams, the Endlers may become stressed due to the high water temperatures. High water temps can have exactly the same effect as low water temperatures.

In Conclusion

Endler guppies are tropical species of fish. They need to live in warm water and it is up to us as fish keepers to provide that warm water for them. For most of us that will mean we have to add an aquarium heater to their aquarium.

There are plenty of reports of people keeping their Endlers at lower temperatures, and they will tell you Endler can ‘survive’ at these lower temperatures. I don’t know about you, but I want my Endlers to do more than just survive!

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James

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