Water Temperature for Guppies?

Topic: I’ve had my guppy tank for a couple months now. I’ve successfully gotten by with NO heater for my aquarium. What water temperature do guppy fish need? I didn’t think they needed heated water but I could be wrong. Tank details: 10 gallon aquarium with 5 guppies. They seem somewhat different lately.. Maybe I’m over thinking this. Could use advice.


*Awarded Answer
Posted by Megan V:
Your aquarium does need a heater and I’m surprised you have gone this long without one. Guppies are tropical fish and the water temperatures need to be in the mid 70s at minimum. I imagine your fish are starting to be put under stress from it. Guppy fish call out for tropical water conditions of 70-78 degrees Fahrenheit. If your tank isn’t within that range constantly… then you need a heater. I’m trying to hold back on being mean, but you need to better research your pets before you just dump them into a habitat. Your fish could easily die from a variable like this that you neglected to follow. When buying an aquarium heater, figure on 5 watts per every gallon of water in your tank. So.. you said your tank is 10 gallons, that means the heater needs to be 50 watts. Local fish stores overprice heaters so I suggest buying online. Here is a top rated one with hundreds good reviews.

Posted by James H:
Guppies are from tropical climates so your tank needs to be of tropical temperatures. You need a temp of 75-80 degrees Fahrenheit. It’s very important to have the correct water temperature for tropical fish. You may be able to hold down that water temperature if you live somewhere with warm weather. If you need to buy a heater, figure on needing 5 watts for every 1 gallon of water in your aquarium. You said your tank is 5 gal so that means you need a 25 watt aquarium heater.

Posted by Jake N:
Pretty common beginner mistake so I wouldn’t sweat it too much (but do take care of it). If your serious about owning a fish aquarium, a heater will be something you use all the time. Maybe you even want to get one that is a bit larger for future upgrades?… Ten gallon tanks are so small and almost useless for anything other than live bearers or Betta fish. I’ve always kept my tanks around 77 Fahrenheit or above.

Posted by Kevin D:
You will quickly realize that most fish that you keep in aquarium are going to be tropical but there are a few that are Coldwater habitat like the goldfish. Even when I told for snow I personally just used heater just because I would prefer warmer water if I was a fish. It kind of sucks because heaters are somewhat expensive for larger aquariums but once you have it it’s one of those things that you won’t need again. Just part of the cost to have a fish aquarium I guess.


Posted by Brandy D:
You can actually find heaters on craigslist for very cheap. If you look under aquariums you will notice that people are selling all of their stuff combined as one price but if you offer them like $5-$10 they’re usually going to take it I have done this numerous times for my multiple tanks. I problem was that I had multiple tanks and I just cannot afford to be spending $40 on heaters for each tank individually. I would actually advise just to get on craigslist and look for an aquarium set up for sale.

Posted by Kelley N:
I have setup my first guppies tank and I need to know if I need a heater or not? What water temperature do guppies need in a smaller tank? I have a 5 gal with around 5 fish in the tank. I’m wondering if I made a mistake of not buying a heater for my little Fishies. Can someone help me that has experience keeping these fish. Please and thank you.

Posted by Sarah E:
I live in Florida and that is technically a tropical habitat so none of my tanks need heaters. But my cousin lives in Minnesota and he has to heat his water so much that it brings up his electrical bill. It is important to have the correct water temps for your fish though. I highly advise you take action on getting a heater if your water isn’t at the right temp range. I did a bunch of research on the best brands with reviews

Posted by Pete M:
It seems like a lot of those beginner set ups that include a small tank will also come with heaters and filtration systems built into them. I see them all the time at Walmart and other pet stores are they sell them as a bundle package and it’s almost a good idea to just get it all at once if you’re in the beginning stages. The main problem with a lot of those bundle packs is that the heater is very underrated and even when you go to Walmart to buy aquarium heater they are regulated properly. Just like somebody else stated you need 5 W per every single gallon of water and if you look at the description of these heaters that are sold at Walmart and large retail stores they’re very under rated underpowered.

Your aquarium is really small and I would advise that if you have hopes in getting more fish that you’re going to want a bigger set up. I don’t mean any offense by it just trying to speak from one aquarist to the other. There is always room for upgrades.

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