Guppy fish make for an excellent beginner-friendly fish species that can thrive in both home aquariums and outside ponds.
If you’ve landed on this article, you’re probably trying to figure out the right temperature range for guppy fish and whether you can keep guppy fish in cold water like the one that’s preferred by goldfish and koi fish, for example.
You may also wonder, whether guppy fish need a heater in their tank, and in what conditions can you keep guppies in outside ponds, especially if you live in a temperate climate.
All these are valid concerns that I’m going to address in this article and help you figure out the best way to ensure optimal temperature conditions for your guppies.
I’m going to preface everything by saying that guppy fish are not truly comfortable in cold water and it’s unadvisable to keep them in temperatures that are way outside their preferred range.
Keeping Guppies in Cold Water
If you research guppy fish, you’ll quickly find out that they are tropical fish, which means they have a marked preference for warmer waters.
Their ideal temperature range is set between 72-82 °F (22-28 °C). That said, guppy fish can survive in lower temperature water that goes as low as 60 °F (15 °C). They keyword here is survive, which is far from thriving or enjoying water at that temperature.
Plus, I’d say that water with a temperature that low is far off from their ideal range, which opens up the way for diseases, breeding problems and lowered activity levels.
Guppies kept in aquariums that are that cold will stop breeding and become inactive. They’ll also become highly susceptible to diseases that can eventually lead to their death.
So, if you’re planning on keeping guppies, it’s best to offer them the right conditions and not expose them to potentially deadly temperatures.
All this raises the question whether guppies can be kept in outside ponds, especially if you don’t live in an area with tropical climate.
Keeping Guppies in Outside Pond
Guppies will enjoy an outside pond, especially if you live in a climate where temperature during the winter doesn’t drop below 68 °F (20 °C).
If you live in an area like this, you can keep guppies in outside ponds or tubs all year round, without having to use a heater or having to transfer them inside during the winter.
The situation is different in areas with winter temperatures that drop below freezing level. In these areas, keeping guppies outside all year around is out of the question.
If you live in an area with chilly winters and autumns, it’s best if you set up your outside ponds in the spring when temperatures no longer drop below under 64 °F (18 °C).
The sun during the day will make the water warm enough to keep the water warmer even during the night, so during late spring and summer keeping them outside is all right.
As soon as autumn comes by, you should move your guppy fish inside, where you can set up a heater for their aquarium and keep them in their optimal water temperature.
Using a heater outside is not economical, and it’s best if you have them in an environment where you can better control the temperature or where there isn’t such a big temperature difference.
Why You Should Use a Heater with Guppies?
I often come across the question if guppies need a heater in their aquarium. Most of the time I recommend using one except for those in tropical climates where sudden temperature changes are not an issue.
Guppy fish don’t tolerate variations in their aquarium water temperature, in fact, they require stable water temperature, which can only be achieved through temperature control.
If temperatures fluctuate, they become susceptible to diseases because their immunity weakens, and they become stressed.
Therefore, I recommend using a heater to keep water temperature stable in the aquarium. Otherwise it’s difficult to monitor and adjust water temperature and there is a high risk of diseases.
And preventing fish diseases is so much easier than treating them, especially that many guppy fish diseases can be difficult to treat or even impossible to treat.
If you don’t want to invest in an aquarium heater, here are my suggestions for other fish that you should keep instead:
Other Fish that You Can Keep in Cold Water
Some fish will do fine in colder water or even appreciate colder water much more than any guppy fish. Some of these fish you can consider are:
Goldfish tolerate temperatures in the 40-78 °F (5-23 °C) range, but fancier strains should be kept in water between 68° and 74° F.
These fish will grow large and require enough space in their aquarium, they also produce a lot of waste, which means their water should be changed regularly and filtered properly.
Goldfish are beginner-friendly fish and do well in home aquariums provided they have enough space and optimal water conditions. They’re also compatible with a lot of freshwater fish.
Suitable for community aquariums and easy to keep, there are several barb fish species that do well in water that has a temperature in the mid 60 °Fs and even a bit lower.
You should consider gold barbs, green barbs, and rosy barbs if you want to set up a community tank or a species-only aquarium that doesn’t necessarily require a heater.
White Cloud Mountain Minnow
Another fish that does well at around 60 °F is the white cloud mountain minnow. These fish are good for beginners, easy to keep and stay relatively small (they average at 1-1.5 inches).
They should be kept in schools and they are extremely peaceful fish that can be kept in a community aquarium if that’s what you want to set up.
They have fluorescent, shimmering colors that become paler if the water temperature is too low. Still, if kept constantly at higher temperatures (above 72 °), their lifespan will shorten.
Water in the mid 60 °F range is also suitable for zebra danios, which are brightly colored, easy to breed fish, suitable for beginners.
They have a fast-paced lifestyle so while they’re suitable for community aquariums, they should not be kept with mellow, slow-moving fish that would become stressed out by their pace.
Zebra danios require open space for swimming, and they should be kept in schools, regardless of their variety, because they don’t do well if kept single.
Bloodfin tetras tolerate temperatures in the mid 60 degrees, although their preferred range is 72°F- 78°F. However, many aquarists keep them in home aquariums without a heater and report having no issues with them.
They should be kept in a school and do well in community aquariums. Because they are top dwellers, you should definitely have a cover for your aquarium as they can easily jump out.
If they’re not kept in a large enough school, they can show aggression towards other fish, but other than that they’re compatible with a variety of species.
Pearl danios are another fish species that can adapt to lower temperatures without issues and unlike zebra danios, they don’t need to be kept in schools.
Their hardy nature and beautiful colors make them an excellent choice for beginners. They should be kept in heavily planted tanks and should be kept in groups of 5-6.
Because they have a shy nature, they should be kept together with fish that have a similar temperament.
Buenos Aires Tetra
Undemanding fish that are easy to care for, the Buenos Aires tetra is a community-friendly fish that enjoys grazing on plants, so careful if you add them to a planted aquarium. Artificial plants can be a good alternative.
They tolerate temperatures in the mid-60s and large, open space should be provided for them in the aquarium as they’re highly active fish.
Although generally peaceful, avoid keeping them with smaller fish or fish that have long fins as they tend to nip at other fish when hungry.
Other fish that are suitable for cold water aquariums include koi fish (ponds), croaking tetras, some loaches like the hillstream loaches and weather loaches, wimple fish, etc.
When searching for cold water fish, you may see the guppy fish featured on some lists, however, guppies are tropical fish and even though are considered hardy, cold water is not their ideal environment.
They may do fine for a while, but the chances of them developing diseases is also high, so why risk it? I recommend keeping them in temperature-controlled environments to avoid issues caused by sudden temperature changes or low water temperature.
The list of fish you can keep in cold water I provided isn’t exhaustive and there are other fish that can be kept without a heater, but the ones I mentioned are the most commonly available.
If you insist on keeping guppy fish, make sure to invest in a heater if the temperatures in your area fall outside the tropical areas where guppies are native to.