AquaMiracle Mini Aquarium Heater 20W Small Fish Tank Heater for 2-4 Gal Tanks, Digital Display Thermostat Betta Heater with Dry-Run & Overheat Protection, Memory Function

Sam, our unexpected Betta fish birthday gift for our 7-year-old, quickly became a beloved member of our family. To ensure his happiness and comfort in his new home, we had to learn the ropes of Betta care. It was surprising to discover that these little fish, often sold in deli containers at pet stores, require a considerable amount of care. During our research, we learned that Betta fish thrive in water temperatures between 78 to 82 degrees Fahrenheit, and achieving this meant we needed 5 watts of heating power per gallon. That's why we found the 20-watt heater to be a perfect match for our 4-gallon tank.This compact heater was an ideal solution for our uniquely shaped round tank, where our only option was a fully submersible heater. Many other models we came across were bulky and had no suitable attachment points. However, this heater's strong suction cup allowed us to discreetly position it near the rim of the tank, preserving the tank's aesthetics. Not only has it maintained a consistent water temperature of a perfect 80 degrees, but it's also safe to touch, as Sam often swims close to it without harm.One feature we appreciate is the easily visible digital display, which helps us monitor the temperature and ensure Sam's safety. However, my one concern is the auto-shutoff setting, which is set at a rather high 97 degrees. Knowing that Bettas cannot survive in water temperatures exceeding 86 degrees, I can't help but worry about the possibility of returning home to an overheated tank.

The media could not be loaded. I absolutely love this little heater! It’s the perfect size for my betta tank, and it does exactly what it promises. The adjustable temperature feature is spot-on, and it holds the temperature consistently without any fluctuations. I was pleasantly surprised by how reliable it is for such a compact heater. It’s discreet, easy to install, and doesn’t take up much space in the tank. If you’re looking for an affordable and efficient heater for your betta or small aquarium, this is definitely the one! I’ve attached a video showing how well it works in my tank.

Like the heater and the fish loves the heater but I wish the cord could bend a little more

Bought the 30w heater for my 6 gallon cube. I had it set to 76 while I was cycling the tank. Put a thermometer into my tank after 2 weeks and it read 72 degrees. So I assume that it's just inaccurate and raised the set point to 86 degrees. Guess where that got me after 30 hours? You're right! 74 whole degrees! You know what the ambient temperature in my house is? You guessed it! 74 degrees! This thing can't even take the 6 gallon nano cube over ambient temperature? Or should easily be able to atleast keep it 5 degrees warmer than my house. Waste of money, I don't suggest buying this. The built in thermostat on it it says it's at 82.5 degrees but the tank is at 74 degrees i have to throw an a 50w heater in now.I had high hopes because I really wanted something easy to hide in my nano tank, no I get to slap a huge 50w heater in there in complete disappointment. I can't even send it back because I'm past the return window now. But I don't even think this 30w heater could maintain a 3 gallon tank.Manufacturer feel free to get in contact with me about your worthless product. Either you have absolutely no quality control/testing or your just pushing a product that you know is garbage and won't work right. I usually ignore bad reviews when I read them but everyone else with the same issue is spot on.

**Updated Review** This seller immediately responded to my review and sent me a replacement. My replacement heater works great and I am very happy with it! My original heater plugged into a USB port, the new one has a normal two-prong plug. I'm not sure if that's what made the difference but the new one works really well. Thank you seller!!So sad that this product does not work. I bought it for my 1 gallon, small fish bowl to keep my beta warm as we live in cold climate. I have had it set to 79F for 24 hours and so far it hasn’t gotten warmer than 74F. Additionally, I used a thermometer to test the water temp and it read 4 degrees colder than the display was reading on this thing. Very frustrating. Save your money.

This heater works perfectly for my 2.5 gallon betta tank! It's little and takes up very little space. Install was extremely simple, and it works great!

Small but mighty. I’ve always had to use a large heater in my small tanks and hated them. This one does the trick. And it’s easier to set temps