Platy fish are one of the first fish that many lifelong aquarists start out with, including myself. They come in an assortment of color morphs and you can easily have an aquarium full of just platies that hit every color in the rainbow.
Platies are also inexpensive and hardy, making them a good option for a child’s first tropical fish tank. And you are almost guaranteed to see babies, which are a great experience if you are interested in raising the fry.
Introducing Platy Fish
As members of the family Poeciliidae, platy fish are closely related to guppies, mollies, and other live-bearing aquarium fish. Livebearers are some of the most popular fish in the hobby for several good reasons.
They are very hardy, eat almost anything you offer them, and come in a wide range of colors. Each species is also very easy to breed and have fry that are large and simple to care for. In short, platies and their relatives have all of the qualities you’d want in an aquarium fish.
Where do Platy Fish Come From?
Platy fish come from Southern Mexico and Central America, in bodies of water that are neutral to alkaline in pH. Their genus name is Xiphophorus, making them close relatives of the swordtail, another hobby favorite. Platies don’t have swords and are noticeably smaller and chunkier than the longer, larger swordtail.
When we talk about platy fish there are actually two species we need to consider. The first is Xiphophorus maculatus, the Southern or Common Platy. And the second is Xiphophorus variatus, the Variegated Platy. Most fish are Common Platies but Variegated Platy Fish are not that hard to find.
The difference is mostly in the form: X. maculatus is a much chunkier fish, both in males and females. X. variatus, on the other hand, is noticeably slimmer. The wild color of X. variatus is a unique reticulated scale pattern that’s very different from X. maculatus.
These days both fish have interbred a lot in pet stores so you can find color characteristics from both fish. Use their body size as the primary guide to identifying which species you likely have.
Platy Fish Types and Breeds
Something to wrap your head around is that there are a lot of platy fish types. And by a lot, we really mean a lot. Similar to koi fish, are a handful of base pattern arrangements that the other platy fish breeds are built from.
The standard patterns include the Tuxedo, Comet, Rainbow, Salt and Pepper, Variegated, Wagtail, and Mickey Mouse Platy Fish. Most platy fish Petco has on stock will be one of these types.
However there is a considerable amount of overlap in the different forms because they all interbreed with one another easily. They can all have different base colors as well. So you can have a Salt and Pepper Mickey Mouse Platy, and so on. But platies that only have the characteristics of a single breed are held in the highest regard.
- Common Names: Platy Fish
- Color Morphs: Panda Platy Fish, Mickey Mouse Platy Fish, Blue Platy Fish, Red Platy Fish, etc
- Scientific Names: Xiphophorus maculatus/variatus
- Origin: Southern Mexico, Central America
- Length: 1½ – 2 inches
- Aquarium Size: 10+ gallons
- Temperament: Peaceful
- Ease of Care: Very Easy
Caring for Platy Fish
As a decades-long aquarium staple, caring for platy fish is a very easy thing to do. Even beginners are likely to have great success at keeping and breeding platy fish.
Platy Fish Size and Aquarium Selection
Both Southern and Variegated Platies are pretty small fish. They don’t get much larger than 2 inches in length, making them perfect residents for aquariums 10 gallons size. Of course, if you buy a larger tank, you can keep even more of them. Which is tempting, considering how many color morphs there are to choose from.
A more spacious tank also helps any babies that are born survive. A spacious tank gives the fry more places to hide until they grow large enough to not be easily eaten by the parents or their tank mates.
Live Plants and Decorations
Platy fish do very well with live plants. They are very good algae eaters, something not many people realize about them. They aren’t as dedicated as mollies, which eat huge amounts of algae. But they do pick at green algae and other types regularly, browsing in between meals. By eating algae from plant leaves they help keep plants healthy and able to photosynthesize at full capacity.
If you choose thick and tightly bunched varieties like Cabomba, Hornwort, or Guppy Grass, you can also provide the platy fish babies with places to hide as they grow up. Platies are also very delicate when eating algae and won’t damage fine leaved plants as they graze.
As midwater dwellers you can also place decorations throughout the tank so long as it doesn’t obstruct all of their swimming space. Driftwood is a popular choice; just don’t add too much because the tannic acids it contains tends to reduce water hardness and alkalinity. Platy fish prefer these conditions (see below).
Platies Fish Water Conditions
Another reason why platy fish are so popular is because they thrive in tap water that is only treated with basic removal of chlorine and chloramine. In many countries tap water tends to be hard (mineral-rich) and alkaline (pH 7.0+). Some fish, such as Tetra fish and Discus fish, do very poorly in these conditions but platies fish actually prefer it.
Temperature-wise, you should aim for moderate conditions. 72-77℉ is a perfect range for them and they don’t appreciate temperatures much colder or warmer than this. Remember, they are from Mexico and aren’t equatorial. So temperatures should never exceed 80℉ except for disease treatments and other brief events.
Platies are also very resistant to higher than normal levels of ammonia, nitrite, and nitrates. That does not mean you should be lax with aquarium maintenance since these compounds still cause them stress.
It just means that they will survive levels that can kill more sensitive fish. Platy fish are often the first fish used to cycle a new aquarium for this reason. But you can also use a fishless cycling technique with ammonia in order to not cause your fish stress.
What do Platy Fish Eat?
Platy fish are some of the best examples of omnivorous fish you will find. As true omnivores they eat both plant and animal matter. In the wild, platies will graze on algae and eat soft aquatic plants, mosquito larvae, water fleas, snail eggs, fish fry, insect larvae and anything else small and edible they can find.
So when choosing a variatus platy fish food, it pays to choose a blend that has whole plant and animal ingredients. I always read the ingredients label and look for spirulina, krill, whole fish, and other additions.
Live and frozen options like brine shrimp, bloodworms, tubifex, and so on are also good food for platy fish. If feeding live food, just make sure that you trust the source since they can carry bacteria and parasites that infect your aquarium pets. Frozen food brands kill any pathogens in the freezing process with minimal impact on nutrition, which makes them a safer and more convenient option.
Platy Fish Tank Mates
Platy fish are popular choices for peaceful community aquariums because they are peaceful and easy going pets. They are not at all aggressive towards other fish and only occasionally aggressive towards one another.
Male platy fish will sometimes chase each other for access to females. And they will chase a female around that they sense is ready to breed. Sometimes they also chase females that aren’t interested, which may result in her turning around and chasing him off. But these toothless little livebearers rarely cause stress or harm to one another.
It is much more important to choose tank mates that won’t cause them any trouble because platies are neither aggressive nor territorial. They also can’t defend themselves against toothy fish like cichlids. Even some of the smaller dwarf cichlids, like Apistogramma, can be a bad option. But German Blue Rams often get along very well with platy fish.
Tetras, Dwarf Gourami, Killifish, Barbs, Danios, and other small and peaceful community fish are your best bets. You can also keep them with other livebearers – just be aware that they will interbreed with many of them, including their close cousin the swordtail fish.
Platies also get along well with bottom dwellers like Corydoras, Plecostomus, Dwarf Otocinclus, and others. Just be certain that if you choose algae eating fish then there is enough for all since platy fish also eat algae. Otherwise you will have to offer supplemental algae wafers and/or vegetables for everyone.
Platy Fish Breeding
Assuming you keep your platy fish well fed and give them good conditions you are guaranteed to see some babies sooner or later. But here are some tips to increase your chances at platy fish breeding.
Sexing Female and Male Platy Fish
The first thing you should know is how to tell the difference between female and male platy fish. Fortunately, it is very easy to sex these fish as they are strongly sexually dimorphic, meaning you can tell the sexes apart by looking.
Sexually mature male platy fish have a rod-like anal fin that’s really a specialized organ called the gonopodium. It is analogous to the penis in mammals: it allows the platy to internally fertilize the female. This is part of how these fish give birth to live babies.
Males also do almost all of the chasing. If you see one platy fish chasing another it is almost always a male chasing after a female or shooing away a rival male.
Female platy fish are a little larger and chunkier even when they are not pregnant. Their anal fin is fan shaped and normal looking. During the last of the pregnant platy fish stages you may see a dark gravid spot just above this fin.
This spot is actually the wall of her ovary that swells and darkens when she has babies. The gravid spot is easy to see in light colored or very pregnant platies. But a dark colored or lightly pregnant female platy may not show a gravid spot much or at all.
Once a male fertilizes a female it takes around 21 days for the fry to develop within. However guppies and many other livebearers can store sperm for a long time. So you may be suddenly surprised by a pregnant platy. Even a female living alone can suddenly become pregnant if she was inseminated in a pet store aquarium before you bring her home.
Caring for Baby Platy Fish
But once she is carrying fry it will likely be obvious unless she does not have very many babies inside. The number varies wildly from a handful to dozens at a time.
Baby platy fish are also very large compared to most fish fry. This is a competitive advantage that is the main reason why these fish have live babies. Each baby is born larger and better developed and are able to fend for themselves more easily.
The platy fry start swimming on their own very quickly after birth and will start looking for food in just a day or two. The fry are already large enough to eat baby brine shrimp nauplii, which are just the right size and wiggle in a way that they won’t be able to resist.
The babies will also graze on algae and other biofilm growing in the tank. Supplement this with crushed flakes as well so they get used to prepared food early. Young platies grow quickly and will be large enough not to be eaten by their tank mates in several week’s time.
In Conclusion
Considering how hardy and affordable they are, caring for platy fish need not be a complicated affair. They are some of the most beautiful aquarium fish you will find and come in just about every color variety under the rainbow. And best of all, they are extremely easy to breed.
Platies were my first aquarium fish and inspired me to continue setting up fish tanks for decades to come. I hope you will also be inspired by these fun little livebearers.
More Frequently Asked Questions about Platy Fish
Still looking to learn more about the cute platy fish? Then take a look through these frequently asked questions about them.
Platy fish are somewhat social and do enjoy each other’s company. A pair will do well on their own in a 10 gallon tank with a few small tank mates. You can also keep them singly with other community fish. Or in larger numbers. But it is always better to keep more females than males since multiple males chasing a female can be very stressful for her.
Platies are some of the easiest aquarium fish to care for and are a great choice for beginners. They are undemanding in terms of water quality, eat almost anything, and are super easy to breed.
Platy fish size is very reasonable; 2 inches is about as large as any female will ever get. 1½ inches is much more common for them, though.
Platies are peaceful and not at all territorial so they will leave their tank mates alone. They may find dwarf shrimp and other small invertebrates a little too interesting and might try picking at them. But other fish and larger invertebrates will all be safe from their curiosity.
