What Are The Water Parameters For Molly Fish?: Ideal Parameters For Their Health

Some people often mislabel Molly fish as betta fish, which is incorrect. What makes them different is their need for a large surface area to swim in and their desire for faster currents than what’s present in homes. Many people don’t realize that mollies require different water parameters than what they would find at home. So it’s important to provide ideal water parameters if you want your Molly fish to be happy and healthy.

The ideal water parameters for Molly fish include a pH level from around six to eight, a water temperature of seventy degrees Fahrenheit or twenty-one degrees Celsius and moderate hardness. What also makes them unique is their specific need for salt in the tank, as it helps with their osmoregulation process.

The bottom line is that Molly fish require special care compared to other fish, including unique water parameters. So this post will be all about caring for Molly fish and ideal water parameters for their healthy lifespan.

What Type Of Fish Is Molly Fish?

Molly fish originated from the fish of the Poecilia genus. These fish are freshwater fish that can be present in many parts of North America, South America, and Africa. They are tropical fishes, making them a great addition to community tanks with their peaceful temperament.

Molly fish come in various colors and patterns, making them attractive to any aquarium. In addition, Molly fish are livebearers because they give birth to their young instead of eggs like most other fish.

What Are The Ideal Water Parameters For Molly Fish?

The ideal water parameters for Molly fish will depend on the type of Mollies you want in your tank. It is because mollies come from different habitats. Therefore they can live happily and healthily in different habitats.

Some of the ideal water parameters for Molly fish are:


The ideal temperature for Mollies must be between 70-80 degrees Fahrenheit. These fish are tropical fish, so they do not tolerate cold temperatures well. If the temperature is too low, Molly fish will become lethargic and may stop eating.

To fish like Mollies living in natural water sources, you need to be very careful about the tank’s living conditions.

So, their artificial inhabitation inside the tank should be a freshwater temperature anywhere between 70°F-82°F (21.11°C-27.78°C).

pH Level

Molly Fish are native to alkaline water habitats, so the ideal pH level for Molly tanks should be seven-eight. Molly fish do not tolerate acidic water very well at all! If you have a caustic tank or pond, Molly fish will become stressed and may stop eating.

It would help if you always kept in mind that the water they naturally inhabit is slow-moving, warm, and slightly alkaline.

Water Hardness

Mollies are typically freshwater inhabitants but are also compatible with brackish coastal sea waters, saltwater, and swamps. Over the years, they have adapted to several water conditions, so they can also be found in rivers, small pools, wetlands, streams, and coastal regions.

In a home aquarium, the mollies are suggested in a tank with a water hardness of 15-30 dGH with a sandy substrate at the bottom and live plants to create a natural environment.

Regular Water Exchange

Molly fish need clean water to survive. So, you should regularly exchange the Molly fish tank water. If you do not, Molly fish will die of Ammonia poisoning and other health problems from dirty aquarium water.

You should be regularly changing 25% of the Molly Fish tank water weekly (if there are less than 15 mollies in your Molly Fish Tank) or 50% of the Molly fish tank water if your Molly Fish Tank has more than 15 mollies.

Filter Out Water Impurities And Waste Products

Molly Fish is very sensitive to ammonia and nitrite and will die if the Molly fish tank water has these chemicals. Therefore, Molly Fish Tank filters should filter out ammonia and nitrite from Molly Fish tank water before reaching dangerous levels. 

Water Filtration For The Tank

We don’t, for sure, know about the need to mix salt in the water yet. But, regardless, the regular change of water is a must-to-do task.

Not only for Mollies but the water in the tank containing any species should also be changed frequently. Mollies are prone to various health conditions due to sudden alterations in water quality. Therefore, as an owner, you have to be very cautious during this process.

A filtration system is always recommended and required for any aquarium.

Mollies produce a lot of waste, contaminating the water and the plants and affecting other fishes.

Not only Mollies, all fishes do this, but it’s equally important to maintain water hygiene. It’s like maintaining pollution-less air for humans and other terrestrial beings.

The effect of polluted air might not be seen immediately, but it degrades health. But fishes are more delicate than other animals and need extra proper care. So, adding a filtration system is a smart move to remove debris like excess food particles, fish excretions, bacteria, and harmful chemicals.

Even though the filtration system sounds like a necessity, it can be an option for the Mollies if you have good hands with experience and have been a keeper for years.

It might be easy for you to remove the waste with perfection, but an aquarium filter is recommended for a better cleaning process.

Other Parameters For Molly Fish

Knowing only the water parameters in the tank won’t help you keep molly fish happy. You need to prepare for something more exciting if you want to see proper growth in mollies.

I have listed out some of the things you cannot overlook when it comes to preparing the molly fish tank:

Tankmates For Molly Fish

Molly fish are peaceful, so their tank mates should also be non-aggressive. If the tank is big enough, you can keep Molly fish with Shrimp and Red Cherry shrimp (at least 50 gallons).

Some other tankmates that can live with Molly fish are Platies, Guppies, and Tetra fish. However, it is best not to keep Mollies with aggressive tankmates like Cichlids or Goldfish.

Mollies are very peaceful, but they can be aggressive when put in together with the aggressive-natured fish of other species.

However, they tend to be protective of themselves at other times, so it is safe to call them a community fish, for they do not harm their tank makes.

Like most species, Mollies also live in groups, known as schools. These schools of mollies search the food near the water surface. The females are less aggressive towards other fishes than the males.

Molly Fish Tank Placement

Molly fish are susceptible to light. So it would help if you placed the tanks in a shady area of the house. They should receive at least six hours a day of indirect sunlight. Their tanks should also be in a cool room where the temperature will stay in ideal condition.

Molly Fish Feeding

Molly fish are omnivores to eat both plants and meat, but their diet should mainly consist of algae-based foods and meaty food. It would help if you fed these fish at least two times a day, and fish tank water levels of nitrate, phosphate, and ammonia should always remain as low as possible to ensure the healthiest environment for Molly Fish.

Keep Live Plants In The Water

Molly fish like tanks with live plants because they will eat the algae off of tank live plants. You can also create your Molly fish habitat more natural by adding some real aquatic Plants to the water. But you should avoid putting plastic or silk aquatic Plants in a Molly fish tank as Molly fish may try and nibble on them. Common live plants best for Molly fish are Indian Fern, Java Moss, and Anubias.

Types Of Molly Fish

There are 14 Molly Fish species, but the four most common Molly fish are:

Black Molly (Poecilia Sphenops)

Black Molly Fish is also a type of Molly fish of Yucatan or Swan Island. These Molly fish are native to Mexico, Honduras, and Guatemala, where they can be present in freshwater ponds, rivers, and streams.

Black mollies typically have a dark body coloration, making them readily identifiable from other species of Mollies. As a result, the Black Molly Fish is an excellent community fish that can get along with other Molly fish. The main difference between the black Molly and different types of Molly fish is their dorsal fin, which has a dark edge.

Molly (Poecilia Reticulata)

Molly is another common type of Molly Fish in North America and South America. These fish are native to the US, Mexico, Argentina, and Central America.

They have lighter body coloration than other Molly species with vertical bars on their side, which become progressively smaller as you move up Molly’s body. The dorsal fin also has a sharp edge that is darker in color than its base coloring.

Sail Fin Molly (Poecilia Latipinna)

Sail Fin Molly fish are native to South America, North Carolina, Texas, and Mexico’s Yucatán Peninsula. They have a unique dorsal fin shaped like a sail. These Mollies are usually present in fresh, brackish, and coastal water.

Molly Fish can be present in different habitat types such as jungle streams, rivers, and mangroves swamps along the coast. However, Sailfin Molly’s also grow slightly more significant than other Molly species, making them unsuitable for small tanks.

Common Or Short Fin Molly (Poecilia Mexicana)

Molly fish are another Molly species native to Atlantic Slope from Rio San Juan, Mexico, to Guatemala.

Molly Fish are famous for their short fins, so they are the Common Molly or Short-fin Molly. The Molly’s tail has a dark edge similar to the Black Molly, but their body coloration is typically lighter than other Molly fish with a bright white belly.

Is Molly Fish Easy To Care For In-Home?

Molly fish are one of the most accessible types of tropical fish to care for in-home. These fish only need an average-sized fully cycled tank with clean water and proper filtration systems. Depending on their types, you can house them in freshwater aquariums and brackish aquariums.

Molly fish do not require much in terms of space. They can fit into any home aquarium setup and still be able to thrive. Their care effortlessly; all that Molly fish needs are regular water changes, a healthy environment, a proper food/diet plan, and live long, happy lives!

Molly fish are a peaceful species that will not bother other fish or their environment. These fish are very friendly to humans and different types of tropical fish, especially those in the same genus (Poecilia).

Some FAQs

What Should I Feed My Molly Fish?

Molly fish are omnivorous and will eat most flake food, pellets, or frozen brine shrimp. You can also feed them some vegetables for nutrients like cucumber or zucchini.

Do Molly Fish Need a Friend?

Molly fish are social animals and do best when kept in schools of their kind. However, if you observe a single Molly fish, it may not receive the nutrients it needs to stay healthy from its diet alone. So they must have a tank mate to keep them company and their tanks well-stocked with decorations for hiding places.

What Type of Molly fish Should I Get?

There are two types: short-finned and long-finned Mollies. Short-fins have a more pointed tail than the long-fin Molly’s.

How Many Molly Fish Should I Have?

Since Molly fish are social creatures, you should keep them in groups of six or more to prevent stress and territoriality. So, what is the ideal number of Molly fish for a tank?

Is Molly Fish Aggressive?

Molly fish can be territorial, so it’s important not to overstock your tank with other Molly fish. They should also have enough room for territories and hiding places. Molly Fish are generally peaceful but may become aggressive when spawning or during feeding time.


Summing up, Molly fish are straightforward to take care of in the home. These fish can live in a wide range of water parameters. But it’s always best to do your research before you get any new pet so that they have the longest and healthiest life possible. Nevertheless, they are a great starter pet for any beginner aquarist. Molly fish can live up to 3 to 4 years in captivity with the proper care.

Fishkeeping doesn’t need to be difficult, and Molly is here to prove that fact. Molly is one of the most beloved aquarium fishes today because they’re easy-going but still very interesting. These fish can be a great first pet for anyone, and they’ll provide you with many years of enjoyment. This fish is one of the most popular freshwater aquarium species available today because it offers so much.

Molly Fish is straightforward going but still interesting enough to keep any aquarist entertained long into their lives as pets.

If you have any queries or questions, please drop them below in the comment section.

Good luck!!!

Happy Fishkeeping!!