Guppy (Poecilia reticulata)

Guppies are one of the most common fishes in the aquarium hobby. In fact, they have been around for a long time and the aquarium hobby as it is known today probably would not have existed without this fish. While it can sometimes be viewed as a beginner fish, it is so much more than that and here is everything there is to know about these amazing freshwater fishes.


During the initial days of the aquarium hobby when it was still in the process of going mainstream, there weren’t a lot of options when it came to the fish. Transportation by air was too expensive and no other viable way existed to transport most of the tropical fishes available. Only those fish that were small, abundant, and very hardy were capable of being exported which is how the guppy became so popular in the aquarium trade. 


Almost every guppy sold in the hobby today is captive-bred. However, they originally came from the many different freshwater bodies in South America. They also naturally occur in parts of the Caribbean. It is also worth noting that guppies have found their way back into lakes and rivers in countries they did not occur naturally in as a result of being artificially introduced in many places.

Discovery & Etymology

As alluded to earlier, these fish naturally occur in two places and thus they were discovered two separate times. This was first done by German naturalist and explorer Wilhelm Peters in Venezuela in 1859. Two years later, Italian zoologist, Filippo De Filippi independently discovered the same fish in Barbados.

As this fish was discovered twice, it was known by two names initially – Poecilia reticulata and Lebistes poecilioides. Later, it was named the Girardinus guppii after Robert John Lechmere Guppy who was responsible for sending specimens of this fish to the western world and that is how it came to be known as the Guppy. This name has stuck even though its scientific name has changed multiple times after that.


The guppy has been subjected to more than a century of selective breeding which means that the specimens found in the hobby do not show a great amount of resemblance to the ones that occur in nature. However, they all still share a few general characteristics. Guppies are small and elongated with a tail that can be everything from short and round to fan-like and really elaborate. The colors can also vary widely. The markings on the tails can also differ a lot from one guppy to another and can include stripes, spots, and blotches. Guppies can, therefore, impart a lot of color to a freshwater aquarium.

One trait that all guppies share is sexual dimorphism. This is when the male and female differ physically. In the case of guppies, the males are smaller, slenderer, and more colorful while the females are larger, rounder, and not as brilliantly colored. The anal fin in females is triangular while those in males are narrow and pointed.

Aquarium settings

Owing to how hardy they are, there is a common misconception that these fish can be kept in very basic setups that are small and feature minimal to no equipment. This couldn’t be further from the truth. They can survive longer than most fishes in unfavorable conditions but that does not mean that they should be subjected to such conditions. 

Guppies need a proper tank instead of being kept in vases, bowls, or bottles. The tank should be at least 10 gallons in size even though a 20-gallon tank or more is preferable. It is crucial that the tank is fully equipped with a good filtration system and heater. The filtration system should be rated at least 1.5 times the total volume of water in the aquarium. The tank should also be properly cycled before introducing this fish or any fish for that matter. As far as the type of filter used, there is no particular type that is preferred as long as it is dependable. The same applies to the heater. It should be rated for the volume of water in the tank and should be from a reputable brand.

Guppies aren’t very picky when it comes to the tank setup. They can even be kept in bare bottom tanks but it is advisable to have some sort of a substrate as it makes maintaining the tank a lot easier. Guppies make for a great addition in planted tanks but they will do just as fine in a tank with artificial plants or no plants at all. The ideal setup would include a nice mix of open spaces and hiding spots for the fish. As these are active fish, sharp decor should be avoided.

Ideal water conditions

The guppy is renowned for its hardiness and it will be forgiving of many beginner mistakes when it comes to the water conditions. However, it is still a good idea to stick to a certain range for the different water parameters. The temperature should be kept between 68°F and 78°F or 20°C to 26°C. pH can be between 6.5 and 8.0 and the hardness should be between 100 mg/L and 150 mg/L. Even though these fish can tolerate some fluctuation in these parameters, stability is key to their long-term good health and this should be assured as much as possible.


Guppies are very docile and they make for a great addition to a community tank. However, tankmates for these fish should be chosen with care. The first factor to consider is their temperament. Any fish chosen as coinhabitants for the guppy should be equally docile and of a similar size. The size criterion is particularly important as even gentle fish can end up either willingly or unwillingly eating the diminutive guppy if their mouths are large enough. Some great tankmates for the guppy are

  • Mollies
  • Platies
  • Gouramis
  • Cory Catfish
  • Neon Tetras and other peaceful Tetras
  • Swordtails
  • Ender’s Livebearers 

Species only guppy tank:

Given how much variety there is when it comes to the shape and colors among guppies, keeping just a species-only tank is a very viable option even for those looking for a good amount of variability in their tank. There are a few things that need to be kept in mind when going for this approach. Guppies are livebearers which means that they directly give birth to their young instead of laying eggs. They are also pretty prolific at this and the females have the capability to store sperms for a long period of time and across multiple spawnings. 

As such, the right ratio of males and females must be maintained to avoid an explosion in the guppy population unless that is the goal. The ideal male-to-female ratio is 2:1.   


Almost all the guppies found in the aquarium trade are captive bred and this along with their naturally easy-going approach makes them quite easy to feed. They are omnivores and will readily accept almost anything. For their best health, it is advisable to give them high-quality fish food in the form of micro-pellets or flakes that float. There should also be a nice mix of plant and meat-based food. They should be fed at least once a day with only just enough food that they can consume in about five minutes. Along with this, their diet can be supplemented by giving them live food or frozen foods once a week. 


There are few fishes that are as prolific when it comes to breeding as guppies are. In fact, they can give birth to hundreds of young even in a female-only tank thanks to the female’s aforementioned ability to store sperm. If breeding is the objective, then there should be two males for every female. They don’t need any special conditions to induce spawning either. They will mate on their own and the female will eventually become gravid and give birth to about 50-100 young. As these fry are incredibly tiny, they should be kept away from other fish as they will get gobbled up. The males should be switched out after a couple of births to avoid congenital abnormalities and shortened lifespans.

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