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Guppies should not be kept in cold water. As a tropical fish which originates from northeastern South America, guppies need their water temperature to be kept between 72°F and 80°F (22°C and 26°C). Keeping guppies in cold water will make them susceptible to diseases.
Guppies are probably the world’s most popular freshwater fish. They have been kept and bred by both hobbyists and professional breeders alike since the 1960s. Guppies are now available in a wide range of colors, patterns, and tail shapes.
I got my first guppy in the mid-1990s and I don’t think there has been a day since that I haven’t had at least one guppy tank in my fish room. I have kept just about every color and tail shape imaginable.
Can Guppies Live In Cold Water?
Guppies are tropical fish that were originally collected in northeastern South America. Their natural habitats are rivers and streams where the water temperature usually stays in the mid-70°F’s (low-20°C’s).
As guppies have evolved to live in these warmer waters, they can become stressed when exposed to colder water for prolonged periods of time. Stress is a major killer of guppies. It is important to maintain the water temperature in a guppy aquarium to prevent them from becoming stressed and ultimately, sick.
When I first started keeping guppy’s 30 years ago, there were lots of stories dating back to the 1960s and 1970s that said ‘in the old days’ guppy breeders would expose their guppy’s to low water temperatures for prolonged periods of time to make the breed stronger and the fish hardier. It was claimed they could keep guppies as low as 65°F (18°C).
Professional breeders today tend to be based overseas rather than in the USA. Countries like Thailand, China, and Malaysia are famous for their guppy farms. Not only does their climate tend to be more tropical than in the US, but the guppies are also being bred in state-of-the-art facilities where entire rooms are heated.
Rather than guppies being hardier through exposure to cold temperatures, they tend to be more and more reliant on the water being warmer and warmer.
Can Guppies SURVIVE In Cold Water?
Guppies will usually survive if they are exposed to cold water for a short period of time. When we ship guppies around the country they are often exposed to cold temperatures, but only for a short period of time.
A couple of years ago the heater in one of my guppy tanks failed whilst I was on vacation. When I returned home I realized the problem straight away. The thermometer on the aquarium was reading 67°F (19°C). I swapped the heater and my guppies were fine. They had only been in cold water for a maximum of 5 days and they didn’t show any long-term health issues.
Had they been in that cold water for longer, the stress may have led to Ich or a bacterial infection taking over the guppies.
What Happens If Guppies Are In Cold Water For Too Long?
When guppies are forced to live in an unheated aquarium for a prolonged period of time, their stress levels rise quickly.
Research has shown that prolonged high-stress levels in fish cause them to become susceptible to diseases and bacterial infections. Ich, if present in the aquarium, can quickly overcome a stressed guppy. Fin rot and bacterial infections also take advantage of a guppy’s compromised immune system.
The other major issue that can affect guppy’s living in cold water, is their inability to digest food. When a guppy’s core temperature drops too low, its metabolism slows right down. Instead of food taking a couple of hours to pass through the guppy, it can take a couple of days.
During this time the food starts to rot inside the guppy and can give off gases which cause the guppy to swell up.
What Is The Best Temperature For A Guppy Aquarium?
A Guppy aquarium needs to be maintained at between 72°F and 80°F (22°C and 26°C). If temperatures stray too far above or below this temperature range, the guppies may become stressed and a stressed guppy is susceptible to infections and diseases.
I set the aquarium heaters in my guppy tanks to 76°F (24°C). That way, even if the temperature fluctuates slightly, either way, the guppies are still in their comfort zone.
Guppies are tropical fish and need to be kept in warm water. Their aquarium should be maintained at between 72°F and 80°F (22°C and 26°C). When the water temperature is outside this zone, our guppy’s health may suffer.
I recently wrote an article titled Do Guppies Need A Heater? which looks at the issue in greater detail.