Choosing the best aquarium heater can be vital for the health of your fish. Your aquatic friends need a stable, fish-friendly environment in which to thrive for the longest possible lifespan. For some, water temperature is one of the most important sustaining factors. So it’s important to take some time to explore the available products and their proper use.

Why You Really Need An Aquarium Heater

There are a few species of fish and some aquatic plants that do not require a heater. However, the most common aquarium residents will suffer without some temperature regulation (CO2 regulation is important too). Fish cannot regulate their body temperature internally. They rely on the ambient water climate to keep their metabolism at optimum levels.

For either freshwater or saltwater tanks, a temperature of 76º-80º F is ideal for most fish species. That’s warmer than most people like to keep their homes, so a reliable aquarium heater is needed to maintain aquarium health.

A heater will also prevent unwanted fluctuations that can be harmful for your fishy friends. This is especially important during cold weather. A good aquarium heater will have a thermostat that tells the heater when to turn on and off, allowing for very little change. If you are hoping your fish will breed, maintaining a constant temperature becomes even more essential.

Types of Aquarium Heaters

There are several types of heaters in a variety of sizes designed to meet the needs of any tank. You may have a personal preference regarding the type of heater that will work best for you. If you are a new hobbyist, it may worth your while to know how the various types work.

Hanging/Immersible Heater for your fishtank

These heaters generally hang on the side of the tank with the heating element, encased in a glass tube, submerged in the tank. This is the most common heater for beginners. They generally require modification in the tank lid to accommodate the top of the heater where the controls are located. They are very basic and not always efficient and so should be closely monitored. They often come with an aquarium starter kit.

Submersible Heater

Submersible heaters sit completely under the water. They are often attached with suction cups to keep them in place. They work best near the inlet of the filter where they can heat incoming water. The coiled element may be encased in glass or toughened plastic. Plastic is preferable, as it is less prone to cracking. These heaters often have an LED light that indicates they are on. Submersible heaters can help maintain a more stable, consistent temperature in your tank.

Substrate Heaters

Although this type of heater is mentioned here, they are no longer common and can be expensive. They are generally used along with other heaters to help promote plant growth. Substrate heaters consist of wires attached to the base of the aquarium to heat and stimulate roots. If you are developing a large tank with lots of plants, you may explore this supplemental heat source.

best aquarium heater

In-Line Heaters

In-line heaters are used in systems with external water filtration. The unit is inserted into the filter outflow line so that water is heated before entering the tank. It is most popular for larger tank systems or those with aggressive fish, such as cichlids, that may interact with in-tank equipment.

Some hobbyists love not having a heater inside their tank, but some of the drawbacks of in-line heaters are cost and an increased chance of leaks. Also, if water flow should be disrupted, the heater could be damaged or destroyed.

Heater Placement

Where you will place your heater is determined by the size and needs of your tank and its occupants. Heaters should be placed for consistent, uniform heating in every area of the tank. This may mean it will be necessary to use more than one heater or ensure the heater is placed where the water is in motion for best circulation. Also, ensure you purchase a heater that is powerful enough to handle the volume of water in your tank.

Choosing the Best Aquarium Heater

You’ll want to choose an aquarium heater that will be reliable, with easy-to-read displays and cut-off safety features. You should be able to find a dependable heater appropriate for the size of both your tank and your budget.

Maintenance is also important. Try to pick a model that’s easy to clean and maintain in good working order. You’ll want to research the durability of construction materials and how hard it would be to replace broken parts. Follow installation instructions carefully to get the best, longest-lasting performance.

Once you’ve decided what type of aquarium heater would be the best fit for your setup, you can begin to zero in on more specific models. Watch ratings and reviews for helpful customer feedback and suggestions. Here’s a great video on the best aquarium heathers on the market:

The Best Aquarium Heater Reviews

Cobalt Aquatics Flat Neo-Therm Heater with Adjustable Thermostat

This Cobalt heater features a flat design to lessen encroachment into tank dwellers’ space. The heater is fully submersible and can be turned to face inward or outward for greater placement versatility. It can be used for either fresh or saltwater aquariums or terrariums.

This versatile unit comes in several sizes to accommodate tanks from 6-55 gallons. The one-touch control makes it easy to set the electronic thermostat, which maintains the desired temperature to within +0.5°F. The heater’s LED display shows both the set temp and actual temperature at a glance.

This heater is manufactured in Poland and gets high marks for durability. It is constructed with a shatterproof outer casing and a resin/thermoplastic heater. It also includes thermal protection circuitry to prevent overheating. The neo-therm component will automatically shut the heater down if needed. Cobalt bases its ratings on the heater’s ability to raise a tank’s temperatures as much as 11°F above room temperature, making it less liable to becoming overstressed.


  • Completely submersible
  • Easy to set up
  • Safety cut-off and shatterproof case
  • Modern, flat design


  • Expensive
  • Suction cups may fail and need to be replaced
  • Some customers have sited a short lifespan for product

Hydor In-Line External Heater

The Hydor is designed for external use only, attached to the return line of a filter or sump. It is easy to use and suitable for either fresh or saltwater aquariums. The heater must be installed vertically and its weight should be supported using the attached loop to prevent stress on the canister filter.

The Hydor features positive thermal coefficient (PTC) technology as a guarantee against damage from overheating. The unit can even remain undamaged if left running without water for a short time. The heater comes with 12-16 mm of piping, depending on the desired size. The connectors are suitable for most of the commonly used flexible pipe used by external filters. It has an easy to set and easy to view temperature control.

The patented heating element replaces traditional metal resistor coils with a special polymer sheet that has been silk-screened with heating ink. It is completely safe and UL listed. It comes with a special cleaning brush for easy maintenance.


  • Very safe
  • High quality
  • Simple set up
  • All maintenance can be performed outside the tank


  • Turns on/off frequently with a clicking noise
  • Some filters may need adapter connectors
  • Some report temperature fluctuations

Aqueon Pro Submersible Aquarium Heater

The Italian-made Aqueon Pro is a highly durable aquarium heater that can be used for fresh or saltwater aquariums. Its almost indestructible construction features an aluminum core and a shatterproof, non-corrosive shell. The heater is completely submersible and can be well hidden either horizontally or vertically.

The Aqueon Pro’s adjustable, electronic thermostat’s heat settings range from 68 to 88°F with a +/- 1° accuracy. The LED light is always on, showing red when the unit is heating and green when it’s not. It includes an auto shut-off in case of overheating, and the heater resets once it has cooled.

The Aqueon Pro comes in five size choices designed for consistency and dependability. Installation is easy with the included suction cups. For temperature accuracy, make sure the large adjustment knob is centered on the desired temperature.


  • Ultra-durable construction
  • Horizontal or vertical placement
  • Automatic shut-off/reset
  • Lifetime warrantee


  • Temperature dial difficult to set accurately

Tetra HT Submersible Aquarium Heater

The Tetra HT is designed for aquariums between 2-10 gallons with hoods or glass canopies.

It is completely submersible and blends into the background of your tank whether installed horizontally or vertically. If you’re a beginning hobbyist, this economical heater may be a good choice for you.

The heater has an indicator light that shines red when the heater is on and turns green once the correct temperature has been reached. The built-in electronic thermostat automatically maintains tank water at 78°F, which is great for the tropical fish chosen by most beginners.

This heater should be placed inside the aquarium before it’s plugged in, as it will begin working as soon as power is supplied to it. Please read installation instructions carefully before use.


  • Small size
  • Pre-set thermostat
  • Affordable price


  • Only two smaller sizes
  • No dry safety feature

Fluval E Advanced Electronic Heater

If you live in the UK, here’s an aquarium heater with a 3-pin UK plug and free delivery for you. The unit features precision temperature control with a digital microprocessor to monitor and display your tank’s water temperature in either Celsius or Fahrenheit. It also includes an integrated fish guard to provide extra protection for your tank inhabitants.

The heater comes in four sizes for a wide range of wattage choices. The fully-submersible heater has an LED indicator alarm for if the temperature exceeds pre-set levels. Its slim profile can be adjusted without removing it from its mounting bracket for a sleek, inconspicuous look.

The Fluval E’s backlit readout is easy to read at a glance. The heater features some of the most advanced technology available, such as fast heat with a built-in warning and shut-off feature for low water levels. Reading customer suggestions will help in adjusting the heater for consistent performance.


  • Choice of three wattages
  • Stylish, slim design
  • Increased safety with two electronic thermostats
  • Easy access temperature switch


  • Temperature can vary up to three degrees
  • Requires a high water flow
  • Higher priced


Whether you’re a beginner or a pro, the best aquarium heater for your specific aquatic friends can be found with a bit of research. For beginners, the Tetra HT is a proven brand for basic, easy to use installation and functionality. For dedicated hobbyists with larger setups, the Aqueon Pro is a top pick for providing a stable, consistent heat source.

As a precautionary measure, it is always a good idea to purchase a couple of smaller back-up heaters to help sustain your tank if your main heater should malfunction. A dependable aquarium heater can mean the difference between life and death for your aquarium friends, especially during colder weather.

With today’s technology, an aquarium heater need not detract from the beauty of your tank. Rather, it can aid in your enjoyment of healthy plants and fish. So when you’re ready to set up your tank, don’t forget to choose a reliable heater to help ensure lasting success.

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