Do Endlers Need A Heater? {5 Reasons Why You Don’t Need One}

Should you use a heater when caring for Endlers? Can they survive without one of will it cause stress? In this article, we’ll find out if Endlers in your tank should be cared for with a heater.

Do Endlers Need A Heater? Endlers aren’t wild caught from their native location in tropical South America. Although they qualify on most lists for cold water fish,  72°F and 82°F (22°C and 28°C) is an ideal temperature range. If you can maintain that through winters and nights without a heater, then you don’t need one. 

What Is The Ideal Temperature For Endlers?

Your endlers have been bred in captivity. They are active breeding livebearers that thrive under set temperatures. The range is quite high for endlers:

  • 68°F-82°F (20°C and 28°C)

We tend to believe a better starting point is 72°F, but even though their metabolic function will slow down when it gets cooler, they are hardy enough to withstand it.

The focus should be to prevent sudden rises and drops. This is why a heater helps. It isn’t just for warm temperature, it’s about consistent conditions. Endless temperature fluctuations may leave your endlers stressed.

Why Do Endlers Need A Heater?

The native freshwaters of northern South America is close to the equator. These tropical conditions can be mimicked in places like Thailand or Florida where the mass breeding of endlers has become popular.

The water in captivity tends to be warmer than the coolest night in their native waters at around 68-72°F (20-22°C). Although the difference is small, so are your endlers and their fry.

Slight temperature changes for captive endlers produces stress, lethargy, illness and early death. If you wish to breed endlers, you need to maintain the temperature at a set level.

What Size Heater Do Endlers Need?

Your tank size will determine the best choice for a heater. Do not be overwhelmed by the multitude of options. Choose a heater that has a plastic guard to prevent your endlers from getting too close to any glass or plastic heating tubes.

The heat won’t need to be set high, but having a thermometer included with it would be nice. This way you can check if there are fluctuations.

The general rule of thumb is usually:

  • 5 watts per 1 gallon of water

Here are your options that focus on wattage only:

  • 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
YouTube video

When Do I Not Need A Heater For Endlers?

If the information in this article is contradictory to many lists of cold water fish, then it’s done so on purpose. We are not advising against keeping your endlers without a heater.

We only wish to profess that we have had better luck and healthier endlers when we have maintained a set temperature of 75°F. You can choose to set your heater anywhere near this range and it will work to maintain it at or around this number.

5 Reasons Why You Don’t Need A Heater

The following five reasons make it less necessary to use a heater for endlers:

  1. Your water temperature never fluctuates higher or lower than 68-82°F.
  2. Ambient air temperature is never lower than 68°F or higher than 82°F.
  3. You don’t wish to breed endlers. 
  4. You want cooler temperatures to calm aggressive or hyperactive endlers.
  5. You want warmer temperatures to prevent parasites or increase endler activity.

Young endlers will be more sensitive to stress, but if you’re not breeding them, it won’t matter. Cooler temperatures slow down their metabolic function and calm things down.

If you want your endlers to be more active or you want to keep parasites away, then higher temperatures will help. Increased heat may shorten their lives, but your endlers may breed more often.

What Happens When My Endlers Get Cold?

A slower metabolism from constantly cooler temperatures of 68°F or lower may cause the following reactions:

  • Endlers will slow down
  • Their offspring will grow slower
  • Females may end up in a longer gestation period
  • Stress
  • Illness
  • Parasites (Ich)
  • Excessive hiding
  • Frequent Shoaling

It’s best to maintain the temperature with a heater. They are cheap, lightweight and easy to set up.

Can Endlers Live At Room Temperature?

If you reside in similar climates to Florida, Thailand or Venezuela then you may be able to keep endlers outdoors. If you want to keep them indoors, you can mimic these set temperatures with your thermostat in your home.

You can use radiators, central heating and air conditioners. If you plan to leave for a trip, you must be able to maintain these temperatures at about 72-82°F. A heater in the tank will be cheaper and easier.


You will ultimately decide if you want to use a heater or set up a cold water tank. The latter option was more popular when heaters were larger and more expensive.

Newer, sleeker and cheaper models make it easier for any endler enthusiast to accept that even though their fish may not need a heater, getting one isn’t a bad option.

Make sure your fish are well fed, swimming actively and enjoying their life. If this is happening, you don’t need anyone telling you what to do.


Thank you for stopping by at for all your informational needs concerning the fish you wish to keep in your aquarium. We have plenty of articles on a wide variety of marine life that may also pique your interest. See you again soon!

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.

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