Are Dalmation Mollies Aggressive?

Dalmation mollies are beautiful species that can be breed successfully in a community tank. However, questions, as regards the aggressive nature of dalmation mollies have surfaced among intended fish keepers.

So, are Dalmation Mollies Aggressive? dalmation mollies are naturally non-aggressive. However, there are some precautions and exemptions you need to consider, which we will discuss further in this article.

Dalmation mollies are suitable for some particular species in the same fish tank. Also, they can be in danger when you place them with some dangerous species like male betta.

Dalmation Mollies Nature

Dalmation is a type of Molly fish that you can acclimate to full-strength seawater. Also, they enjoy eating algae growth, as they love gazing and nibbling at every patch in an aquarium. Studies have shown that a lot of Mollie’s variety – including dalmation mollies, are the product of multiple breeding.

Meanwhile, some are the product of different types of Mollies, while others are product interbreeding Mollies and Guppies. Also, dalmation Mollies are somewhat aggressive when a male species is placed in the same tank with another species.

Moreover, a mating process between two opposite sexes of dalmation Mollies may the reason behind the aggressive nature you are observing in your dalmation Mollies.

Dalmation Mollies Morphology

Dalmation mollies are native to Central America. Also, they are a type of molly classified under the species, Poecilia sphenops. Moreover, they are also known as “shortfin”. Fortunately, they are easy to care for, and breed for beginners.

However, this is more possible when you put the same-sex of dalmation molly together. Therefore, they can be difficult to breed if you put the opposite sex together in the same tank, as they are known as prolific breeders.

Moreover, to avoid mixing the characteristics of dalmation with other varieties, you should bear in mind that other species are classified into the same group as dalmations.

These common species include Lyretail, Black, Sailfin, Liberty, Mollie, Ballon, Golden, Mexican, Short-finned, Piebald, Ghost Pearl, Red Sunset, Gold Dust, Pointed Mouth, etc.

  • Size of Dalmation Mollies: They are small and slender in body. Also, their size is about 3inches for big males, and 5inches for big females. Moreover, they have a smaller dorsal fin than that of sailfin.
  • Coloration: They don’t only exist as monotone color, but also have gold varieties. Moreover, some have gold patches on them, while others have an entirely different color all through their body.
  • The appropriate PH level, temperature and water hardness for dalmation mollies are 7.5-8.5, 70-degrees Fahrenheit to 82 degrees Fahrenheit and 10 degrees to 25 degrees DH respectively.
  •  Also, it is good to add some salt to their aquarium water. Moreover, this shows they can stand a salinity water condition. But this isn’t necessary, as it doesn’t contribute to their lifespan or longevity.
  • Dalmation mollies have a lifespan of 3-5 years, which varies depending on the care given to them by the fish keeper.

Breeding Dalmation Mollies

The mating period is one of those situations where you may find your dalmation molly exhibiting some aggressive trait.

However, compare to some other types of fish, they are usually easy to breed. But, if they are not properly cared for, it may lead to hurting one or more of your fish.

Here are what to consider before putting your dalmation fish in the same tank for mating;

Male-Female Ratio: It is preferable to have female to male molly in the ratio 3:1 in the same tank. Also, if you want to prevent having fry all the time, it’s better to have the same sex in a tank or the female species than male species.

Moreover, if the males outnumbered the female molly, their appetite is often aggressive. In return, the female will feel harassed, lost her appetite and thereby, die as a result.

Moreover, the dalmation Mollies breeding process is usually easier, as the females are mostly larger than the males.

Mollies Disease

Aside from the aggressive trait that dalmation mollies exhibit towards the opposite sex or the same gender as the case may be, other factors contribute to the loneliness of a naturally aggressive fish. Likewise, a fish keeper should pay attention to the traits each fish exhibits.

Moreover, when a dalmation molly is inactive, it moves slowly, which may be due to some common diseases. Some of these diseases symptoms are;

  • Shimmy: Shimmy is a disease that appears in many diseased molly fish. This is a symptom of many possible diseases. Moreover, to kill this symptom, you should treat it at the onset with molly bright medication or shimmy block.
  • Torn fins: This may be a result of a fight from an aggressive fish or fin rot. However, if it is a case of fin rot, you need to determine whether it’s fungal or bacterial. So as to determine its adequate treatment. Regardless, you should separate the molly fish first, and treat it with disinfectant.
  • Dropsy: Dropsy may be a symptom of many fish diseases, including fish tuberculosis. This is seen in fish when their midsection is extremely swollen. And in severe cases, mollies scales stand upright.
  • Constipation: Constipation in fish is when the belly is very distended, or the fish releases stool frequently.
  • Lethargy: Lethargy is mostly a result of pregnancy.
  • Dull white film on skin: This could be an Oodinium or fungal infection. However, to determine which case it is, turn off the tank light and on a torch. Moreover, it’s Oodinium if the white patch glows back, and if the white patch appears furry – like a mound, then, it is a fungal infection.

Other signs in an unhealthy dalmation fish;

  • Popeye
  • Sunken belly
  • Reddened/purple gills
  • Flashing/Scratching
  • Gasping for air on the surface
  • Slanted swimming

Related Questions

There are other related questions that many people have always seem to inquire answers to, concerning dalmation mollies. Some of these questions include;

How Can I Tell If My Dalmation Molly Is Male or Female?

Female mollies have normal triangular anal fins. Whereas, males have pointy-shaped anal fins, which is referred to as, gonopodium.

How Do I Know If My Male and Female Dalmation Are Mating?

At this phase, the male will frequently chase after the female, which may be misunderstood for aggression. Moreover, the male will point his gonopodium towards the female’s belly.

Why does my donation fry disappear?

Dalmation mollies and their other tank mates can feed on their fry. In most cases, the fry is usually trapped under gravel. However, the fry ceases to be in danger as soon as they are too big to fit into the molly’s mouth. Also, to save the fry before they grow to a bigger size, you can provide hiding spaces in the tank, such as mini pots or jars on the substrate, stacked flat marbles or a floating plant. Moreover, you can place the female molly in a separate tank, before her birth. However, the initial is preferable, as isolating pregnant female mollies stresses them out.


We hope this article has helped unravel uncertain questions as regards dalmation mollies, especially if they are aggressive or not. Having established that dalmation mollies are peaceful species, however, it is important to put into action the stated tips, and cautiously follow the measures to prevent harm to any of your fish.