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Best Aquarium Heaters for 2023

Aquarium heaters have a vital job – heating and regulating the temperature of your fish tank.

Fish cannot regulate their own body temperatures, and many breeds require the temperature to be precise to within a few degrees.

When looking for an aquarium heater, you need something that is really easy to use and set up. You will need to be able to set the precise temperature and then easily monitor it.

You’ll also want key safety features. Look for something that will automatically shut off if there is an issue and an indicator light that tells you when it is on and doing its job.

To help find the right heater for you, we analysed thousands of reviews and dipped into all their pros and cons, before testing the top 17 we found. The best of the bunch are below.

From inline heaters to new-age submersible options, we hope this definitive list will help you find the perfect heating partner for your tank.

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    Our Top Picks

    Image Product Details
    Fluval E Advanced Electronic Heater
    • LCD water temp display
    • Integrated fish guard provides advanced protection
    • Easily adjustable heater bracket
    Check Price
    Marina Submersible Pre-Set Mini Heater
    • Easy to access temperature changes
    • Impact resistant glass and guard
    • Huge choice in other power levels
    Check Price
    AquaEl Ultra Heater
    • Really accurate temperature setting
    • Super thin
    • Easy to set up
    Check Price

    The Top Aquarium Heaters Reviewed

    Fluval E Advanced Electronic Heater

    Providing some of the most sought after and premium quality aquarium heaters on the market, Fluval’s electronic heaters are guaranteed to conjure up a tropical paradise in your very own home!

    These models from Fluval’s E series are currently their most technologically advanced heaters yet and come in varying degrees of power, from 50 to 300 watts, meaning you can power up pools from 20 to 300 litres!

    Equipped with a smart microprocessor monitoring system, Fluval’s product accurately records your tank’s temperature with dual sensor probes, while a precise temperature setting lever allows you to adjust the exact temperature in 0.5 degree increments.

    The combination of these features means there’s no way you’ll never not know the exact temperature of your tank water, with an LCD temperature display constantly keeping you on top of your tank’s heating at all times. Colour changes on the screen will indicate any drops or rises in temperature, and flashing risk screens will warn you of any critical spikes or chills.

    It’s everything you need to ensure the safety and well-being of your aquarium inhabitants!


    • LCD water temp display
    • Integrated fish guard provides advanced protection
    • Easily adjustable heater bracket


    • Weight: 481 g (200w)
    • Dimensions: 5.1 x 2.5 x 31.8 cm (200w)
    • Wattage: 50, 100, 200, 300

    Marina Submersible Pre-Set Mini Heater

    An easy-access temperature controller. Easy to read temperature settings. An impact-resistant glass design in case your fish happen to get a bit giddy when swimming.

    These are just some of the highlights of this mini heater. There is also a bumper guard for their safety, as well as a completely waterproof sealing to ensure it stays working throughout its lifespan.

    Despite its small size, it is mighty. The 50w Marina Submersible Aquarium Heater provides reliable heating for fresh or saltwater aquariums up to 38 litres, so you don’t need a huge heater which takes up all the space to ensure your fish are kept in the correct heated waters.

    The power cord is 1.8m long, which is generous as well.

    This heater may be mini, but don’t worry if you have to get something a little bigger and more powerful – the same heater is available in levels up to 300W, or as low as 25W too.


    • Easy to access temperature changes
    • Impact resistant glass and guard
    • Huge choice in other power levels


    • Weight: 181 g
    • Dimensions: 2.5 x 2.5 x 15.2 cm
    • Wattage: 50

    AquaEl Ultra Heater

    An advanced heater in an unbreakable plastic casing, this heater has a high-precision electronic thermostat, a built-in thermometer, and an overheat alarm.

    Because the casing is unbreakable, it is great for tanks with large fish or animals such as turtles, and it will also protect animals from the heat and eventual burns when getting too close. It is easy to use with a one-touch system, using a single control button with a range of LEDs around the edge which tell you everything you need to know temperature-wise.

    This heater operates with exceptional accuracy (+/- 0.25° C) so a constant temperature is maintained. The heat can range between 20 and 33 °C, which means it is great for treating diseases such as white spots. A built-in system will prevent it from overheating too.


    • Really accurate temperature setting
    • Super thin
    • Easy to set up


    • Weight: 405g
    • Dimensions: 48 x 29 x 165 - 48 x 29 x 210cm
    • Wattage: 25, 50, 75, 100, 150W

    HITOP HP-608 Submersible Aquarium Heater

    If you always feel like you deserve a little extra cherry on top of your cake when you make a purchase, there’s no better aquarium heater goodie bag than this HITOP HP-608 offer, with added sucker cup and stick-on thermometer included!

    And forgetting the bonus items for just a moment, the device itself ain’t half bad either!

    Safe for humans and animals, HITOP’s device boasts a quartz glass material that is actually 33% thicker than the standard seen in most tank heaters, rendering this model completely explosion proof! (That unfortunately just means it’s protected from the heater itself malfunctioning, not a grenade Mr. Bond!)
    A 10-slot multi-branched ceramic frame also takes up just an astonishing 11 inches of room, a smaller use of space than most brands, yet still packing a huge power punch when it comes to heating up your tank!

    With 100, 200 and 300 watt models available, HITOP covers a wide range of tank sizes from 40 – 500L, making it suitable for all kinds of fish and plant life. A high precision control system also allows more accurate adjustment of temperature and this model has a standard range of 20°C – 34°C.

    This makes it the perfect choice for fresh and marine water fish, and would be a welcome addition to the flora and fauna of any aquarium!


    • Explosion Proof: 2mm thickened quartz glass
    • Space saving and higher stability
    • Extra stick-on thermometer and sucker cup included
    • Suitable for both fresh and marine water


    • Weight: 358 g (200w)
    • Dimensions: 34.2 x 8.2 x 4.8 cm (200w)
    • Wattage: 100, 200, 300

    Interpet Deltatherm Aquarium Heater

    A heating system designed for tropical fish favourites, the Interpet Deltatherm is a double insulated and fully submersible model made with the highest quality components.

    Featuring a quick access, top view temperature control, it’s easier than ever to readjust your settings without ever having to remove your device from the tank, and a handy on/off light indicator system lets you know when your heater is in operation.

    The heater itself also has a fantastic temperature range of 16-34 degrees Celsius, meaning despite it’s target fishy demographic, it could also make a fine water warmer for marine and freshwater fish who prefer slightly cooler conditions to their tropical cousins.

    One downside of this system though is that to take truly accurate readings, it needs to be positioned at a diagonal angle, which can obviously be unsightly within your setup if aesthetics are important to you.

    Still, as long as you’ve got an Easter Island Head to hide it behind, it’s definitely a great option for all types of fish!


    • Designed for tropical aquariums
    • Also suitable for marine & freshwater fish
    • Double insulated and submersible
    • Provides range of 16-34°C


    • Weight: 231 g (100w)
    • Dimensions: 24 x 2.2 x 2.2 cm (100w)
    • Wattage: 25, 50, 100, 150, 200, 300

    Hidom Quartz Glass Submersible Fish Tank Heater

    Hidom’s HT range aquarium heaters have been designed and manufactured by industry veterans and this quartz thermostat heater is their latest in a long line of high quality products.

    If you’re someone who is quite obsessed with getting an even distribution of heat across the breadth of your tank, Hidom’s quite frankly bizarre range of available wattage options means you can get as specific as you want according to the size of your aquarium.

    And with those wattages including a pitiful 25w model and a conversely terrifying 500w version, Hidom is undoubtedly the best choice for very small fish tanks with very few pets inside as well as full scale mammoth ones with more visible fish than water.

    A temperature range of 20 – 34 degrees Celsius makes them a great choice for tropical, marine and freshwater fish and a 1.5mm thick glass structure ensures a quick and efficient heat transfer rate.

    Now that’s watt we call an aquarium heater!

    …We’ll see ourselves out.


    • Quartz Glass Thermostat Heater
    • 9 different wattages available!
    • Heat up to a 500L tank!


    • Weight: 295 g (500w)
    • Dimensions: 45.1 x 8.5 x 4.8 cm (500w)
    • Wattage: 25, 50, 75, 100, 150, 200, 250, 300, 500

    Hidom 50w Submersible Aquarium Fish Tank Shockproof Thermostat Heater

    This Thermostat Aquarium Heater from Hidom’s HT series offers high performance water warming for tanks of various sizes thanks to its range of wattage options.

    Utilising the latest in aquarium heating technology, this submersible device includes a simple set-up temperature scale that keeps your tank topped up with warmth and is perfectly suitable for both freshwater and marine tanks, with a temperature range of 16 to 32°C.

    Fantastic for keeping your fish den a visual delight to behold, the heater’s 1.5 metre mains cable means you’ll have plenty of room to manoeuvre when positioning the device within the aquarium, and heavy duty suckers also allow you to provide firm attachment to the side of the tank, keeping it well out of the way.

    Alternatively, if visuals aren’t a necessity, the cable also just offers you a great chance to position your probe in a spot which is going to give the most even spread of heat throughout, keeping all your fishes equally happy!

    For additional safety, it’s extra thick, heat and shock resistant glass structure ensure the core of the heater is also well covered, rendering it harmless should your fish come into contact with the device itself.

    Safe and secure, what more could you want?


    • Ideal for Tropical / Marine or Freshwater Fish
    • Range of 6 wattages for several tank sizes
    • Blast proof design


    • Weight: 191 g (50w)
    • Dimensions: 30.6 x 8.2 x 5 cm (50w)
    • Wattage: 50, 75, 100, 150, 200, 300

    Interpet Delta Mini Nano Aquarium Fish Tank Heater

    This is a slim and compact heater pad with a continuous heating output, which is great if your fish need the warmest possible water.

    It always heats to 5°C above ambient room temperature, and you’re pretty flexible in terms of placement. Pop it under the gravel, tuck it away behind the filter or just leave it on display if you aren’t concerned about the look for optimum results.

    An aquarium thermometer is included so you can monitor the water temperature continuously, and it is the ideal solution for small aquariums up to 20 Litres (4.4 gallons). There are two models available – this 15W, but also a smaller 7W which can cope with tanks up to 12L.


    • Two variations available
    • Low maintenance - just clean once per year


    • Weight: 240 g
    • Dimensions: 5.7 x 8.87 x 2.12 cm
    • Wattage: 15W

    Eheim Aquarium Thermostat Heater

    The EHEIM adjustable heater is an ultra-modern electronic thermal device that utilises the best available technology of today, while staying true to the classic hanging in the water rod design of old.

    Coming in a large range of different wattages, this simple enough looking design is actually constructed with a jacket material made from special laboratory glass, increasing the heating surface and serving as a kind of heat shield for the device. This ensures the optimum amount of heat is evenly dispersed around the tank, with larger wattages ensuring even the biggest tanks can be taken care of.

    A precise control dial at the top of the heater means changing the settings can be somewhat fiddly and of course, wet, however it can still conduct temperatures in an impressive range of 18 to 34 Degrees Celsius.

    So for those who like their heaters to be a quick and easy set-up, it’s a good choice for tropical fish.


    • Shock resistant shatterproof glass tube
    • Heating function indicated by on/off control light
    • Precise temperature dial
    • Temp range of 18 - 34°C


    • Weight: 449 g (300w)
    • Dimensions: 32.5 x 2.5 x 2.5 cm
    • Wattage: 25, 100, 125, 150, 200, 250, 300

    Buying Guide

    How we chose the best aquarium heaters

    We trawled through thousands of reviews, and dozens of forum posts, to ensure all of the products that made our final cut are actually good in real-world settings, taking on board genuine reviews.

    After choosing a final 17 to test, we were able to narrow it down by around half to find the ones we’d be happy using ourselves, and which we all found easy to use.

    What to look for in an aquarium heater

    An important feature is the size of the heater in your tank. You don’t want it to take up too much room. This isn’t only unsightly, but also gives your fish less space, and poses a potential risk to their safety.

    Then it is power. The general rule is 5 watts (W) of heat per 1 gallon of water. This is if you have a lid on the tank, so you may have to adjust this.

    Aside from this, it can be personal preference. You want something you find easy to monitor and control, as well as easy to set up.

    Other Buyers Ask...

    What are the different types of aquarium heater


    A heater that needs to be fully submerged into the water to work, submersible heaters can usually be placed vertically or horizontally within the tank. Submersible heaters are so popular because they work in both freshwater and saltwater tanks and can also efficiently heat all different sizes of tanks.


    External heaters are installed outside of the aquarium and often have a small hose as its heat source which hangs over the edge at the top of the tank. However, due to this very reason, they do not always distribute warmth so well. For small and medium-sized tanks though they are a good option, as they don’t take up room in the small space you have.


    Inline heaters are similar to external ones except they need to be attached to the tank filter system, heating water as it is pumped back in. This can make them fiddly and complicated to set up. They also may need additional parts for them to work properly.


    If you’re looking for something a little more aesthetically pleasing, substrate heaters are often disguised as something like rock, sea bedding or other sealife plants which can be heated via a cable hidden beneath the tank’s sandy base. However, these aren’t particularly practical ways of heating an aquarium and are quite rare.

    Is a heater required for an aquarium?

    If you have tropical fish, you will definitely need a heater. A heater will not only make the water warmer (tropical fish should be kept at around 76° to 80°F or 25° to 27°C) but will also keep the heat consistent.

    This will make your life much easier, as the water won’t be affected by changes in your room temperature, such as cold in winter or heat waves in summer.

    How safe are aquarium heaters?

    People often worry about heaters because the idea of placing an electrical device into some water seems completely at odds with everything we know about electrical equipment.

    However, what you have to remember is that these products have actually been designed for that very purpose and so are actually perfectly safe.

    Like with anything though, they can become dangerous over time if they start to become faulty. So make sure you regularly check over your equipment to ensure they are no broken parts or frayed wires!

    If you’re concerned about whether an aquarium heater could harm your fish, know that this is very rare if they’re set up correctly. It may be worth purchasing a plastic heater guard which is compatible for your heater, so they can’t get anywhere near the hottest part.

    How much does it cost to run an aquarium heater?

    Electricity is expensive in the UK, but the important thing to remember is that your fish tank temperature must be right for your fish, or they will suffer.

    Thankfully, a heater for your aquarium isn’t that expensive to run. The average cost of electricity in the UK is capped at 34p per kWh (March 2023*) meaning that you pay 34 pence for every 1000 watts you use in an hour.

    A 50W heater would therefore cost 1.7p per hour to run. Heaters are generally only on for around 12 hours per day, so this is 20.4p per day, £1.42 per week, or £74 per year.

    More powerful heaters for larger tanks will cost more, but as you can see, fish tank heaters won’t add too much on to your annual bills. Remember to factor in lighting too, but this is usually only under 10W.

    If you’re concerned, position your tank away from draughts which could affect the water temperature and make the heater work harder.


    Can I keep my tank warm without an aquarium heater?

    You would have to keep your central heating on in the colder months and at night when it cools down, and the tank would need to be situated in the perfect place in your home with no draughts or direct sunlight. And you’d have to keep a constant beady eye on the thermometer and make changes if there was something wrong.

    If this sounds complicated, it is because it would be. An aquarium heater could make your life much easier. If the thought of this setup sounds like it is too much, you may be best with coldwater fish.

    Can I use a large heater in a small tank?

    Worried about buying a heater that is too powerful or large for your tank? Don’t be concerned. If your heater automatically switches off when the water is too warm, its size and power won’t have a detrimental effect on the temperature.

    However, you don’t want it to take up too much space, so bear in mind the size and shape of your tank too.