NS wrote,

Hey. I just arrived at my college today and got a fish. I’m currently housed in a triple which leaves very little room for a fish. Before heading out to the store to get my new little bud I was just wondering what type of heater i should use on my 1 gallon corner tank? The tank has an undergravel filter, and live plants will be going in with it to help keep it a healthy and natural place for my new study buddy. 🙂 Please help me out. And unfortunately until I get a new housing assignment my lack of space is causing me to keep this small tank.

A: Congratulations on your new betta and adventures in college. I too lived in a triple as a Freshman and know how tight the space is and just like you, I got my very first betta in college too. They make for a great dorm-room pet as long as your roommates are cool about them.

One gallon tanks can be difficult to heat. The small water volume leaves it open to severe fluctuations and most aquarium heaters aren’t made for such small containers. If your room is quite cool you may be able to use the Hydor Mini-Heater. At just 7.5 watts it is one of the only water heaters made for tiny aquariums. It is important to note that these heaters do not have an automatic shut-off when they reach the desired temperature like most aquarium heaters have (for larger tanks). This means you could easily overheat your water posing a danger to your fish. If you choose to go with a mini-heater you should absolutely have a thermometer in the tank and you should check it frequently. On warmer days you may need to unplug the heater completely.

Your other option is to go without a heater at all. I typically do not recommend this, but if you keep your Betta in a warm, stable location it may be a safer alternative especially if you can’t be around enough to monitor the Mini-Heater.

Mini-heaters can be hard to track down. If you can’t find one at your local fish store you definitely can find them online. Good luck.

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  1. Callahan says:

    Two recommendations from someone who keeps betta males in one gallon tanks.
    The first is that, if the back corners of your tank are well insulated, you might have good luck with a seedling heating pad. (This assumes that the bottom of your tank is made of something that will conduct a little heat.) These inexpensive pads are about 20″ x 12″, but they fold a little, so you can tuck the edges under a table. You can even get a thermostat control for them and program your desired temperature, but that’s not so cheap, I’m afraid. I ran about 60 dollars to get mine. Check your local hydroponic shop (or, if you don’t have one of those, turn to the intertubes).
    The other suggestion takes more room but is cheaper(!) and more reliable. It takes some engineering, though.
    Buy a clear plastic file holder, taller than your fish tank or with something to raise it above the level of your tank. You should be able to find one that will hold about 2 or 3 gallons. Make this your sump! Use a power filter in it, and a heater with a built in thermometer (yes, inevitably this is one one rated for far more gallons than you’re using.)
    Get a container (vase, plastic cup, something) that fits in the plastic sump and is raised to the highest level you want the water level in the tank to be at. Make sure the output of the filter pours into this.
    Then fill the sump to the lowest level you’ll allow the tank to reach (should be lower then the vase/cup reservoir!). Make sure the filter draws water from this lower level. Excess water should be able to spill out of the reservoir into the dirty water. Run aquarium tubing from the high, filtered reservoir into the tank, and from the tank to the lower level ‘dirty’ water. Start a siphon on both lines. Voila! Temperature controlled, filtered water in a relatively small space at a relatively low current. (And, depending on the cost of your power filter and thermometer, <$30)
    If you do try this, crank the heater up about four degrees higher than you want the tank to stay at– it'll reach equilibrium around where you want it.
    This complicated sounding (simple in practice) system is how I filter and heat four one-gallon tanks with four happy boys (and their pet snails) in them. The file container I got at a Bi-mart for all of $4. I leave the latch lid draped across it (it can't latch, because of the tubing) to prevent excess evaporation, and top it off once a week at most.
    But whatever you do, insulate the two sides of the tank (just draping a towel around it would work) that you aren't viewing your fish through– that'll drop the amount of heat radiating out by a full 60%.

  2. Callahan says:

    An addendum to my massive post above– if you do go the seedling heat pad route, try supporting it and/or taping it so that it covers the back two walls of your tank (the ones stuck into the corners). More surface area will be exposed to its warmth, and it’ll solve your insulation problem in one fell swoop.

  3. Christie says:

    Wow, what great comments Callahan. Thanks for sharing your tips. I’d love to see a photo of your set up if you have one.

  4. Anonymous says:

    thanks very much for the tips. got my fish today and am thinking of trying out one of callahans tips since i wont be in the dorm much. however… being in the “heat control room” means i cant have my window open when im not in the room and i so far it has stayed a constant 76 in the tank. so i may be capable of going without a heater at all. not so sure of this in the winter…
    thanks again!

  5. Anonymous says:

    I have a 1.5 gallon bowl for my Betta. Here is a 10-watt heater that is excellent among Betta owners who keep their Betta fish in anywhere from 1 to 3 gallon bowls ((see below)). It’s called the “Marineland Shatterproof 10-Watt Heater”.
    Here is the product description for it:
    “High-tech 10 watt heater perfect for young hobbyists. This sleek, fully submersible heater is preset to maintain a comfortable 78°F – no adjustments needed. Heater shuts off automatically if left out of water and shatterproof casing protects against damage. Great for fresh or saltwater aquariums. The Marineland Shatterproof Heater measures 5-1/4″ and is recommend for aquariums up to 3 gallons. UL-Listed. 5 ft. cord.”
    The sites that offer these mini 10watt Aquarium heaters at the cheapest I could find so far are here:
    Aqueon Mini Heater, 10W
    I also found a couple of the “Marineland Shatterproof 10Watt Heaters” on EBAY.COM for excellent prices from some sellers. =)

  6. Cristal says:

    Thanks for this post! I got ‘Thriller’ just a week ago & I am obsessed with keeping him happy & healthy! I just ordered the Hydor Mini Heater!

  7. Georgina says:

    I have a 1.3 gallon (5L) tank, don’t have a betta yet and i live in New Zealand.
    I decided to get my tank set up first and getting it relatively stable before even thinking about introducing a fish. I started by buying a 10W one of those shatterproof heaters and found it would not heat my tank at night above 16 Celcius (66 ish Farenheit), after this I replaced it with a 25W (same type of heater) which would not heat above 22 (72 Farenheit), exasperated i bought an elite 50W heater which for the last three days has kept my aquarium at a constant 26-27 Celcius (79-81 farenheit).
    I am confused as to how it has taken this much Wattage to heat a small tank and whether I should trust this heater to keep my aquarium constant for my future pet.

    • Christie F. says:

      Your right Georgina. A 50w heater for a 5L tank does seem excessive. Are the heaters you are buying have a dial so you can set the temperature? I have found that they vary a lot and the numbers on the dial mean very little. I always start lower and over the course of a couple of days, dial the heat up until it reaches the desired temperature. The other recommendation I would make is to use an air-stone if you aren’t using a filter to disperse the heat away from the heater and throughout the rest of the tank so that you don’t have a hot spot. And definitely doublecheck the temperature with a second thermometer, just in case it the thermometer that is broken and not the heaters. Please post back if you find out what the problem is. I’m really curious about this one.

  8. kim says:

    One thing I did back when I had a 1 gallon set up with the hydor mini-heater, was to run it on a timer. I can’t remember the exact formula I used but I think I had it set for 2 hours on and 1 hour off. I had a thermometer constantly submerged and monitored the temperature very closely. It stayed relatively consistent and I didn’t really have to worry about overheating. Then I found these 2 gallon jars at walmart for $20 (they look like clear glass cookie jars with a lid) and now I’m able to use submersible 10 watt Marina heaters that maintain the temp at 78% (they work great IMO). I also now run combo sponge/carbon filters. I find having that extra little gallon makes a huge difference in being able to maintain water and control temp…and it doesn’t really take up much more space. BTW Christie, thanks so much for creating this site. This is my first stop online resource I’ve learned so much here.

    • Christie F. says:

      Thanks for the recommendation of running the Hydor Mini-heater on a timer. That’s a great idea!

  9. Maria says:

    I heated a 2.5gal betta bowl with Marineland’s Stealth Submersible 10 watt heater, but it seemed to only be stable when I positioned the heater horizontally. Once I did, it stayed at 78degrees constantly!

  10. Frank says:

    Lets go fishing.

  11. George of the tank says:

    Hi I live in Florida I keep, my Bettas in back yard I have messure temperature day 80 degrees nigth 60 degrees will this fluctuation affect them?

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