Dalmatian Molly 101: Care, Diet, Tank Size, Tank Mates & More

Whether you’re a brand new aquarium owner or you’ve been keeping fish for a while, Mollies are one of the most popular species on the planet. And, of all the different types of Mollies available, it’s the Dalmatian Molly that is arguably the most intriguing.

Named for its white body that is speckled with black dots, the Dalmatian Molly is an excellent addition to both community and same species tanks. They are also pretty hardy and easy to care for.

If you’ve been thinking of adding a Dalmatian Molly to your aquarium but you want to know everything about this beautiful fish before you do, you’ve come to the right place! Below, we’ll take an in-depth look at Dalmation Mollies including tank size, water parameters, temperament, and everything else you could ever need to know. 

Species Summary

It’s easy to see how Dalmatian Mollies got their name. Their overall white coloring is splattered with multiple black dots, just like a Dalmation dog. Of course, this is where the resemblance ends and the two animals couldn’t be any different!

Dalmatian Mollies are a freshwater fish that belong to the Poecilia sphenops family. However, they are also known for their ability to live in water with fluctuating temperatures and quality. This includes brackish waters and swamps, and it’s believed that this ability is what makes them such a hardy aquarium fish. 

Care Guide

Tank Size

Like all fish in the Poecilia sphenops family, Dalmatian Mollies are active swimmers who need a lot of space to move around freely. If you’re setting up an aquarium for the first time, you need a tank that has a capacity of at least 20-gallons.

If your budget can stretch to a tank with a 30-gallon capacity that would be even better, as you won’t be taking up too much valuable space with plants and ornaments.

One thing to keep in mind with tank size, however, is that a 20-gallon tank would only be suitable for one Dalmation Molly. For each additional fish, whether it be more Mollies or other species, you need to add an extra 5-gallons of space to your tank.

Tank Mates

Dalmation Mollies are peaceful, docile fish and, as long as each fish has enough space, they can live quite happily with many other species. Some of the best fish to pair with Dalmation Mollies include:

  • Guppies
  • Endlers
  • Platies
  • Swordtails
  • Neon Tetras
  • Zebra Danios
  • Minnows
  • Corydoras
  • Plecos
  • Gouramis
  • Angelfish
  • Harlequin Rasboras
  • Siamese Algae Eaters
  • Otocinclus Catfish
  • Aquatic Snails

Same Species Tanks

While you can pair Dalmation Mollies with any of the fish above to create a truly diverse aquarium, Mollies themselves come in so many different shapes, colors, and sizes that many people use them in same-species tanks.

Different types of Mollies that you can create a same species tank with alongside Dalmation Mollies include:

  • Black Mollies
  • Dalmatian Lyretail Mollies
  • White Sailfin Mollies
  • Silver Sailfin Mollies
  • Gold Dust Mollies
  • Balloon Belly Mollies
  • Marble Lyretail Mollies
  • Gold Doubloon Mollies
  • Harlequin Sailfin Mollies
  • Platinum Lyretail Mollies
  • Golden Sailfin Mollies
  • Creamsicle Sailfin Lyretail Mollies
  • Red Sunset Mollies

Again, you need to make your start with a 20-gallon or 30-gallon tank and that each additional fish you add to your same-species aquarium has its own 5-gallons of water. 

Water Parameters

One of the things that make Dalmatian Mollies such a popular choice, especially for novice aquarium owners, is that they are hardy. This means that they are able to put up with fluctuations in temperature and water quality without it affecting them too badly.

However, to keep your Dalmatian Mollies as happy and healthy as possible, you should aim for the following water parameters:

  • Water Temperature: 68º-82ºF (20º-27ºC)
  • Alkaline pH Level: 7.0 – 8.5
  • Water Hardness: 20.0 – 35.0 dH

What To Put In Their Tank

There are a few important things that you need to put in an aquarium that is going to be housing Dalmation Mollies. The first, and arguably the most important of these is aquatic plants. 

Aquatic plants serve two purposes inside your tank. First of all, they offer your Dalmatian Mollies (and any other fish that they are sharing the aquarium with) a place to quickly swim to and shelter in when they feel threatened.

Secondly, aquarium plants gather a coating of algae over time and this makes up a portion of your Dalmation Molly’s diet. As such, they become an excellent source of vitamins and minerals for them. 

It’s also important to offer your Dalmation Mollies somewhere that they feel safe to shelter in and that offers more protection than the plants. This could be a cave-like ornament or a piece of decorative driftwood that they are able to huddle behind for protection.

One thing that you do need to remember when putting plants and ornaments into your tank, however, is that they take up space. And, the more space they take up, the less space there is for your Dalmatian Mollies to swim freely in.

With this in mind, choose your ornaments and plants carefully and avoid overfilling the tank. If you do want to make a naturalistic aquatic environment for your Dalmation Mollies using many different types of plants and several different hiding places, you’ll need a much bigger tank.

Common Diseases

Just like all members of the Poecilia sphenops family, there are some diseases that Dalmation Mollies are susceptible to. 

The first of these is Ich. This is a highly infectious disease that can quickly work its way through your entire aquarium, so it’s something that you need to keep an eye out for and treat immediately.

Symptoms of Ich include breathing difficulties and small white spots all over the fish’s body. The fish may also be rubbing itself against gravel or ornaments to try and relieve any itching. 

Treatment involves isolating the affected fish and treating it with an over-the-counter Ich medication. You should also clean the aquarium the fish was living in before isolation, and apply the Ich treatment to the water as a cautionary measure. 

Dalmation Mollies are also susceptible to developing Dropsy. Unfortunately, this is an untreatable disease and it can cause renal failure, leading to a fatality. Symptoms include bulging eyes and protruding scales caused by fluid retention. In this case, you’re advised to take your fish to your veterinarian.

The best way to prevent your Dalmatian Molly from developing either of these diseases is to perform regular tank maintenance. Check your filter and heater systems regularly and carry out partial water changes. And, most importantly, make sure you don’t overcrowd the tank with too many fish, plants, or ornaments. 

Food & Diet

Dalmatian Mollies are omnivorous fish, and this means that they enjoy a plant and animal-based diet. A good-quality fish food should be given each day, but you can also supplement this with live food such as bloodworms, brine shrimp, and tubifex. 

A weekly treat of chopped-up vegetables such as zucchini, cucumber, and romaine lettuce should also be given. Dalmatian Mollies also need algae in their diet, and the best way to do this is by adding aquarium plants to your tank and letting them form naturally on their leaves and stems.

Some of the best aquarium plants for Dalmation Mollies include Java Moss, Java Fern, Anubias, Water Wisteria, Water Sprite, and Hygrophila. 


The average lifespan of a Dalmation Molly is between 3-5 years. However, this depends on the living conditions and diet they have been given. A Dalmation Molly living in an overcrowded tank and fed exclusively on fish flakes will have a dramatically lower life expectancy than one that had room to swim and enjoyed a varied diet. 

Appearance & Size

We know that Dalmatian Mollies are given their name due to the fact that they have the same markings as a Dalmatian. However, there are actually four different types of Dalmation Molly and, although they all have the same black and white markings, their sizes and shapes are different. 

The first type is the Standard Dalmation Molly. These are the most common Dalmatian Molly and they grow to an ultimate size of around 3-inches. 

The next type is the Ballon Dalmation Molly. These have an arched back, a rounded belly, and a lyre-shaped caudal fin. This type of Dalmation Molly also reaches an ultimate size of around 3-inches.

The Sailfin Dalmation Molly is the third type. These have a taller and broader dorsal fin that runs from behind the neck to the caudal fin. 

Finally, we have the Dalmatian Lyretail Molly. These also grow to around 3-inches in length and their most distinguishing feature is their lyre-shaped caudal fin.

Behavior & Temperament

Dalmatian Mollies are among the most docile fish that you can add to an aquarium, which is one of the reasons why they make such excellent choices for community tanks.

However, as with all fish, a male Dalmatian Molly may start to become territorial and display aggression towards other members of the tank if they aren’t given adequate room. 

It’s also worth noting that male Dalmatian Mollies can become aggressive when it comes to mating, especially if there aren’t enough female fish to pursue. Comparatively, female Dalmatian Mollies are entirely non-aggressive. 


Dalmatian Mollies are live-bearing fish, and this means that they don’t lay eggs. Instead, the baby fry come into the world fully-formed. They can also give birth to as many as 100 baby mollies at once!

However, one thing to be aware of is that Dalmatian Mollies can often mistake their own young for food, and they may eat them! For this reason, it’s best to move a pregnant Dalmatian Molly into a separate birthing tank and, once she’s given birth, move her again into another tank. 

Gender Differences: Male VS. Female

There are five signs to look out for when it comes to determining whether a Dalmation Molly is male or female. 

The first is color. Male Dalmatian Mollies tend to have bolder, brighter patterns than females. The reason for this is to make them stand out more when it comes to finding a mate. 

The second size is size and shape. Females are generally larger than males and they also have a more rounded body shape. Males, by comparison, are generally flatter.

You need to turn your attention to the dorsal fin for the third sign. A male Dalmatian Molly’s dorsal fin is larger than the females and, again, this is to seem like more of an attractive mate. 

The fourth place you need to look is at the anal fin. A male Dalmatian Molly will have a tube-shaped anal fin, while a female will have a triangular one. 

The final sign to look out for is their behavior. Male Dalmatian Mollies are flirts and they’ll swim around the tank, showing their fins to the females as a way to attract them.