How to Tell a Molly from a Platy

For longtime at home aquarists, years of experience with both Mollies and Platys might make this an easy differentiation to make. However, for many just getting started with at home aquariums, and for some with plenty of experience, telling apart a Molly from a Platy can be easier said than done.

So, how to tell a molly from a platy? The easiest ways to tell a Molly apart from a Platy are the body shape, size, and color variations. Mollies tend to be longer and larger, with longer fins and snouts, whereas Platys are often stouter and more compact in their design. Additionally, Platys tend to have a much broader range of colors and patterns.

Size3-5 inches2-3 inches
Body Typeelongatedshort, stout
Fin LengthmediumShort
Tank Size20 gallons or more10 gallons or more
Water Typefresh, salt, or brackishfresh

In terms of at home aquariums, both Mollies and Platys are extremely popular for aquarists of all experience levels. Their color spectrums and adaptability make them excellent options for a range of tank sizes and habitat types.

What is a Molly?

A Molly is a small sized tropical fish originating in South and Central America. They are often found in freshwater streams but can also live in salty, brackish coastal waters. This adaptability, along with their small size and beautiful colors, make them incredibly popular amongst aquarists around the world.

What is a Platy?

A Platy is the common name for a small freshwater fish found in Central America. Also, a member of the Poeciliidae family like Mollies, Platies are smaller and have a stouter shape than their cousins the Mollies.

Most platies you’ll encounter in the fish store come from one of two species: the southern platyfish, and the variatus platyfish. These species have been bred into a number of hybrids in captivity to make for a wide range of color and pattern variations.

Do Mollies and Platies Get Along?

Yes, both Mollies and Platies are peaceful species of fish and will get along well if given the right amount of space and habitat to live in together. As with all community fish, the proper amount of space and habitat is important for proper fish health. An overpopulated tank will add stress to all fish in the tank, and too little vegetation and cover can add stress by removing places for fish to hide and rest.

Another important note for those looking to get Mollies of Platies for their tank is noting whether you have fin-nippers in the tank or not. As some Mollies and Platies come with longer fins, you’ll want to be sure that other members of the tank aren’t fin-nipping varieties, as this will add stress to your Mollies and Platies.

What Type of Water Does a Molly Need?

Mollies are incredibly adaptable fish and can survive in both fresh and saltwater. This adaptability makes them incredibly common in community tanks, as they can be added to a greater range of environments than most other types of fish.

In addition to being able to survive in fresh and saltwater, Mollies can also handle a range of both pH levels and water temperatures. Again, this makes them incredibly common for the at home aquarist.

Lastly, Mollies thrive in a planted tank with enough room to swim freely while still providing the occasional coverage. While most varieties of Mollies will survive fine off of the food you provide, some will graze on the tank vegetation, so you’ll want to be aware of whether that’s a possibility for your Mollies.

What Size Tank do Mollies Need?

While the exact size of your tank will vary based on your space and what size community you hope to house in it, for a handful of Mollies a tank no smaller than 20 gallons should be used. Because Mollies are such great community fish, rarely will aquarists have a tank of only them, and therefore will usually have a much larger tank.

The larger the tank, the better you can accommodate the variety of fish you might be hoping to house in this community tank. With more space to swim and more room for cover and vegetation, your fish will be able to find all the elements they need to live a stress-free life.

Additionally, the larger the tank, the less susceptible it will be to rapid fluctuations in water qualities like pH level and temperature. When it comes to at home aquariums, a good rule is to generally go as big as your space will allow.

Can Mollies and Platies interbreed?

While Mollies and Platies are very closely related, they cannot interbreed with each other. Both species of fish are easily bred in captivity and are active breeders. At home aquarists will want to keep this in mind when setting up their tank, as a proper ratio of male to female fish will be necessary to keep the male from over harassing the females.

Mollies and Platies are both livebearing varieties of fish, meaning they hold and develop their eggs inside them until they give birth to live young. This can make for a bit of a surprise for the aquarist if they haven’t noticed that any of their fish were pregnant in the first place.

Idenfiying Different Kinds of Mollies

While there are a number of different kinds of Mollies, as with many other popular aquarium species, they’ve hybridized extensively over the years. This is done to try and isolate the most appealing colors and patterns for future breeding.

That said, there are two main breeds of Mollies: sailfin mollies(poecilia latipinna) and short-finned mollies(poecilia sphenops). Being the most common types, the vast majority of Mollies you’ll find in a fish store will have originated from one of these two types.

While most types of Mollies trace back to one of those two types, there is still a range of types you’ll find in fish stores, with varying sizes, shapes, fin designs, colors, and patterns. Here are just a few of the most common types:

  1. Common Black Molly
    Common Black Mollies are an all-black variety of Molly that sometimes feature color in their pectoral fins. They’re a peaceful variety of Molly, much like all Mollies, and are a fairly hardy and adaptable variety of Molly.
  2. Dalmatian Molly Fish
    Named after the dog breed with a similar color pattern, the Dalmatian Molly fish features an intricate speckling of black and white scales. This variety gets a bit bigger than the Common Black, and require a bit more room to operate as a result.
  3. Dalmatian Lyretail Molly
    A variation of the sailfin, this variety also features the well-known Dalmatian black and white speckled pattern. Slightly smaller than the Dalmatian Molly, the Dalmatian Lyretail reaches only 3 inches in length but features a much more ornate tail that, well, resembles a lyre. This variety also prefers a planted aquarium in the 20-30-gallon range.
  4. Black Sailfin Molly
    Another common option for beginner aquarists, the Black Sailfin Molly is another peaceful, hardy variety of Molly. Featuring a long, sail-like dorsal fin, be careful to not house this variety of Molly with fin-nipping species of fish. Like most other Mollies, a spacious, planted aquarium is the optimal environment for the Black Sailfin.
  5. White/Silver Sailfin Molly
    A captive strain of hybrid Mollies, the White/Silver Sailfin features just that, a white and silver color scheme. Also notable about this variety is the ornate, oversized fins. The females of this variety will tend to get a bit bigger than the males, while the males will often feature a bit more color variety in their scales and fins.
  6. Black Lyretail Molly
    Similar in coloring to the Common Black, the Black Lyretail Molly features white highlights on both its fins and scales. This variety is a hybrid version of the Sailfin and features the same lyre-shaped tail that the Dalmatian Lyretail does. Peaceful and hardy, this variety is another good option for beginners.
  7. Gold Dust Molly
    A brightly colored alternative to the Common Black, Gold Dust Mollies features a bright gold coloration with dusty black patches. Similar in size and tank requirements to the Common Black, this variety is a great option for beginners looking for a splash of color in their fish tanks.
  8. Balloon Belly Molly
    Featuring a shorter, stouter body shape than most other Mollies, the Balloon Belly Molly can sometimes be confused for a type of Platy. Coming in yellow, black, and white variations, this variety of Mollies are peaceful and should be tanked with other peaceful fish varieties. This variety also prefers a more heavily planted aquarium than others.
  9. Marble Lyretail Molly
    Another variation of the Lyretail Molly, this variety features a black and white marbling, with males having a large dorsal fin. Reaching roughly 5 inches in length, these Mollies are a peaceful variety and thrive in planted aquariums. Unlike other Mollies, this variety actually thrives best in slightly brackish water, so plan your tankmates accordingly.
  10. Platinum Lyretail Molly
    Another hybrid variation of the Lyretail Molly, the Platinum Lyretail features an incredibly bright platinum or white body, accompanied by long dorsal fins if given enough space to develop. This variety does well in both fresh and salt water, making them popular amongst aquarists.
  11. Harlequin Sailfin Molly
    This variety of Mollies is one of the larger varieties on this list at right around 6 inches in length. Harlequin Sailfins feature a dazzling color scheme of gold, white, and black patches that make them stand out in just about any community tank.
  12. Gold Doubloon Molly
    A shorter finned variety of Molly, the Gold Doubloon, can be a nice alternative to the Harlequin Sailfin for those looking for a smaller alternative. With a distinctive gold and black color scheme, the Gold Doubloon adds a pop to community tanks. This variety enjoys plenty of space and a planted aquarium.
  13. Golden Sailfin Molly
    Another of the larger types on this list, the Golden Sailfin Molly, is a bright orange colored variety that grows to about 6 inches in length. With a large dorsal sail, this type adds a flare of color to community tanks. They thrive particularly well in open, planted tanks with hard water.
  14. Creamsicle Sailfin Lyretail Molly
    Another of the Sailfin hybrids, this variety also features a lyre-shaped tail fin. Peaceful and hardy, the orange and white colored Molly is another common choice amongst aquarists of all experience levels.

As you can see, there’s a wide variety of Mollies that you’ll find at the fish store. The variety in colors, patterns, and fin designs, in addition to being such adaptable and hardy breeds, is what makes them such a popular community tank choice for aquarists around the world.

Identifying Different Kinds of Platies

Most platies are a hybrid version of the two common species previously mentioned, the southern platyfish and the variatus platyfish. Similar to the Molly, due to their popularity amongst aquarists, Platiess have been bred to create the most visually appealing colorations and patterns.

While most Platies are actually hybrids of the two most common species, there are still a number of commonly recognized hybrids amongst fish stores and aquarists. Here are some of the most common types:

  1. Gold Red Platy
    This variety of Platies have bright gold and red scales with a rounded belly. Their tails can be the same color or a more translucent hue than their scales. Some will also feature a black tail and fins.
  2. Neon Blue Wagtail Platy
    Wagtail is a common feature in many Platies, describing bright colored fish with black caudal and dorsal fins. This specific variety features an eye-catching color scheme of bright blue and purple, contrasted with the black fins.
  3. Mickey Mouse Platy
    Commonly found in red or blue coloring, the Mickey Mouse Platy gets its name from the Mickey Mouse shaped black mark found at the base of its tail. This variety is incredibly agreeable with other varieties of peaceful fish and is incredibly hardy in a variety of different water parameters.
  4. Parrot Platy
    This variety of Platies is known by the distinctive V-shaped pattern on their tail. They come in gold, yellow, and red, and are one of the more popular varieties in North American fish stores. Parrot Platies are also a hardy variety of Platy, able to live in a range of water parameters.
  5. Hifin Tuxedo Yellow Platy
    Hifin Platies differ from some of the other common Platy types in a number of ways. For one, they tend to be more elongated than their stouter relative. They also display a wider range of coloration and patterns than other common Platy types. They also tend to have longer fins, so you’ll want to keep these away from fin nipping species.
  6. Pintail Rainbow Platy
    While much rarer than the Hifin variety, the Pintail Rainbow is pretty easy to identify thanks to the rainbow coloration is exhibits. Rainbow Platies also have a distinctive tail shape, that features an elongated middle section, though this should not be confused with the Swordtail variety of Platy.
  7. Tuxedo Platy
    Another common member of community tanks, the Tuxedo Platy features a black posterior portion contrasted with a brightly colored anterior portion – like a tuxedo. When sold in fish stores, this variety is often named by its color, i.e., Tuxedo Red or Tuxedo Green. This variety thrives in a planted tank.
  8. Panda Platy
    Getting its name from its black colored tail contrasted with its brightly colored body, the Panda is a type of Wagtail Platy. This variety is closely related to the Green Swordtail, and can even interbreed with them. They are a peaceful species and can thrive in a range of water parameters.
  9. Black Hamburg Platy
    While vaguely similar looking to the Tuxedo Platy, the Black Hamburg is not quite the same. With no black tail or dorsal fins like the Tuxedo Platy, the Black Hamburg does feature dark coloring running from the base of the tail to its head, with a usually brightly colored head and belly.
  10. Gold Twinbar Platy
    Gold Twinbars are some of the more brightly colored Platy varieties and features black edged caudal fins. These Platies thrive in a range of water parameters and pair well with other peaceful species. As a schooling fish, they’ll need room to move freely within their environment.
  11. Rainbow Platy
    Generally smaller than other Platy varieties and coming in bright coloration, the Rainbow Platy is a common presence in at home aquariums. Coming in a range of colors, including yellow, orange, red, and iridescent colors, Rainbow Platies prefer a planted tank with hardy plant types to avoid overgrazing.

As a diverse and hardy species of fish, Platies are a great option for any at home aquarium, but especially for those just getting started. As a peaceful species, they pair well with other peaceful species, and their size makes them great for community tanks.