hygger 50W Mini Submersible Digital Display Aquarium Heater for Small Fish Tank, Compact and Fast Heating Thermostat, with External Controller and Built-in Thermometer, for Betta, Turtle

I bought this for my Marineland Portrait 5-gallon aquarium, and it fits in the back where the pump and filter media are located so it isn't in the front of the tank where the fish are. It keeps the temperature exactly what it is set to. It's fairly easy to adjust 1 degree at a time upwards. If you need a lower temperature than what is displayed, you have to keep pressing the adjust button until it goes to the maximum then rolls around to the minimum and starts going up again from there. Would be nicer if it had a down degree button instead. But since you just set it and then leave it, it's not a big deal really.

Put this in my fish tank and it worked great. Turned it up a couple degrees at a time (quite slowly so as to not cook my fish).So far it has kept the tank at a constant temp. The heater was easy to use, easy to install. Sticks great. Only thing thats a pain is that you cant click down a temp. You can only click up until it reaches the highest temp then restarts at the lowest temp. So you have to cycle through it like you would an oven clock. It doesnt actually raise the temp that fast so you dont have to worry about that cooking ur fish. Just keep clicking until it reaches your desired temp. I have one of the sticker thermometers on the side of the tank, it read roughly the same temp that the heater showed it set at (once given time to settle).Update: its been ~9 months and the heaters temp display is off. Its randomly jumping from 73 to 84 deg.... I keep thinking it has cooked my fish but when I feel the water temp it is only 73 (also according to the sticker thermometer on the side its still 73/74). This is the 3rd time it has done it in the last 2 weeks.... I can reset it by unplugging it for 30sec and plugging it back in but sadly Im probably going to have to search for a new one :(

This heather is definitely the best I’ve come across so far. I tried a couple from Walmart and other local pet stores but I ended up with a betta fish after my friend bought my 2 year old one for his birthday. I, of course, was not prepared and I’m not suppose to have a tank in my rental. . But guess what.. I did it. I have a 3.5 gallon tank. (Please don’t read that and judge me. I know I need a 5 gallon but I had to get what I could afford and still a good environment.)This heater did and does wonderful! It actually keeps the water warm unlike some I’ve tried. I was super worried about frying my fish! I’ve read horror stories about some brands and it made me question whether or not to even use one. DO IT. USE A HEATER. USE THIS HEATER!Like anything else, keep a close eye on it for a couple days and keep check on the thermometer. This has digital temperature control which makes it easy to adjust as needed. This is helpful if your power goes out a lot like mine.I’m not sure how to speak on accuracy as my tank thermometer is slightly off. I feel like this is relatively accurate.

I wish I could give it a -5. I don’t normally write negative reviews, but I have to, since I’m so upset with how this item performed.I purchased a 50w mini heater for my 1.7 gallon aquarium that includes 1 male betta fish named Poseidon. I had set the heater to 76 F in the evening. Usually water temperature for a betta can ranger from 72 F-82 F. I went out with my sister to eat and when I came back at 9:00 pm, everything appeared okay. My betta was swimming fine and chilling in his rock as normal. At 4:00 am, I was woken up by my cat. About a minute into waking up, I noticed that my fish’s breathing was heavy and he had difficulty swimming...showing red flags of stress. while looking into the matter, I noticed the water was hot to the touch.I quickly removed the heater which read on its digital screen, 76 F. I used a thermometer to assess the actual temperature; it read 100 F. I immediately began doing about a 20% water change with cold water to try and even out the temperature, while being diligent in not stressing him any further. After 15 mins of doing the water change, he started improving and wasn’t showing any signs of stress.The user manual and what’s posted on the product’s description advised that the item is a “perfect heater” for a 0-13 gallon aquarium. I have worked with different heaters when I had my fish in a 5.5 gallon tank and NEVER went through this experience. Unfortunately, I had to downsize my fish’s tank due to down sizing my home. However, I was simply looking for a small heater that would work well for my fish’s current tank size.Also, the heater’s size is pretty bulky for what’s advertised, that it can be in tanks smaller than 6 gallons. I’m currently looking into mini 10w heaters. Luckily, my 3 yr old betta fish did not die, but I will not be purchasing from this company or seller again.

My AC broke this summer, of course. Meaning my fish room has been upwards of 90° during the day, i have had to retire this heater from use as the tank I had placed it in was only getting up to 70° (I keep separate external thermometers on all my tanks) despite this heater thinking that it was in the mid 80s. I would much rather it err on the side of caution and am I suppose glad for the inconvenience however it does detract from my overall like of the heater.Also, it makes an audible sound like a tea kettle. However it only turns on rarely so I don’t hear it often and it isn’t very loud, but I could see some people disliking it immensely

It took a long time to start, but it's a champ. We use it to heat water in our greenhouse to keep it warm during the winter.