What’s The Difference Between A Molly and A Platy?

The aquarium hobby is a world full of exotic tropical fish. In many cases, the most beautiful of tropical fish are those that are friendly, community fish and suitable for housing in peaceful community tanks. 

Two of these such fish are mollies and platys! If you’ve seen these gorgeous fish in stores, you know that they look quite similar. 

So, the question of the day is what’s the difference between the two? Are they the same species going by different names? Let’s find out!

What’s the Difference Between Mollies and Platys?

The technical difference between mollies and platys is that they are two distinct fish species. Mollies are from the Poecilia family while platys are from the Xiphorporus family, which means that even though the two species look alike, they can’t interbreed. 

The easily observable differences, however, include the size and color of these fish — all of which tend to differ slightly but stay within a general range based on species. Breeding practices are another area where the two species differ. 

Mollies vs. Platys:  Key Differences 

Size

One of the most common ways to tell mollies and platys apart is by looking at their size. In general, platys are smaller than mollies. Reaching a maximum size of roughly 2.8-inches, the size of patys differs further when you consider the size difference between males and females. Females are larger, coming in at an average of 2.5-inches, while males rarely exceed 2-inches. 

Mollies, on the other hand, are larger in general than both male and female platys. Mollies average 4-4.5-inches once full grown, making them substantially bigger. Like platys, female mollies are usually bigger than males, with sailfin mollies of both genders often exceeding 4.5-inches. 

Color

Although there can be exceptions, a general rule of thumb is that these two fish exhibit different coloration. Mollies most commonly come in color varieties that use cooler colors such as blues, greens, muted or dark oranges, and white, while platys are found in more vibrant, warm colors like yellows, reds, oranges, and white. 

Both species can have black markings, patches, or dappling mixed in with their colors. 

Breeding 

Platies reach sexual maturity by foru months of age, while mollies reach this stage around 8 weeks. The gestation period of the female platy is 24-30 days, after which she gives birth to anywhere from 20-80 fry. The female platy will often cannibalize some of her young, which is why aquarists who breed their platys are recommended to remove the fry as soon as possible after they are born. 

Female mollies can hold sperm within their bodies for months, producing multiple batches of young after each successful mating session. The gestation period for mollies is about 60 days and after gestation, the female births 20-150 fry per batch. 

Mollies vs. Platys: Similarities 

Optimum Environment

The ideal tank conditions for these species are very similar. They do well in water temperatures of 75-80 degrees Fahrenheit and thrive in water with a relatively high PH level (7.5 to 8.5). In addition, they require an efficient filter that removes waste and prevents it from gathering at the bottom of the tank. A good filter is especially important since both species are notorious for the amount of waste they produce. 

In terms of substrate, just about anything goes with these species. Mollies would prefer a substrate that contains crushed coral, but the fish aren’t too particular about what’s on the bottom of their aquarium since they don’t spend much time down there. Common substrates for a platy-molly setup include glass rocks, gravel, sand, crushed coral, and of course, bare bottom. 

Tank decor should include plenty of places to hide, some greenery with areas that are more dense than others, and open space for swimming and interacting with the other members of their school. 

Birthing 

These colorful, lively species of fish are livebearers. This means that once the incubation period is complete, the female gives birth to live, fully formed fry instead of eggs that would need to develop and hatch. 

Behavior

Both mollies and platys are known for being friendly and peaceful, which makes them great additions to community tanks. They are schooling fish, meaning that they do best in groups of 5 or more of the same species. This being said, they can be included in an aquarium that has other peaceful fish of roughly the same size, so long as they are allowed to school with their kind.

Many aquariums contain both mollies and platys, as they get along well and have a very low chance of fighting or displaying aggressive behavior. In both species, however, there can be slight aggression when the male to female ratio is incorrect. The correct ratio for maintaining peace is one male to every 3 females. 

Also, keep in mind that both species are incredibly active and social, which makes it crucial for you to have enough space in your aquarium for them to explore. 

Diet

Platys and mollies are both omnivorous. This means that they should be fed a mixture of plant and meat-based foods. This can be achieved by feeding pellets designed for either carnivorous or herbivorous fish and fulfilling the other portion of the diet with the correct foods. 

They can eat algae and an assortment of blanched vegetables like spinach, lettuce, and zucchini, as well as the occasional high-protein snack of bloodworms, brine shrimp, or daphnia. 

Conclusion

When all things are considered, mollies and platys have more in common than they do different. They are, however, distinct species that have their differences, with color, size, and breeding habits being some of the more prominent differentiating factors. 

These two species can live peacefully together despite their differences, as they have similar temperaments, environmental requirements, and diets. In fact, an aquarium with schools of both these fish is, in our opinion, incredibly eye-catching and serves as the focal point of the room in which it’s located.