How to take care of Molly Fish?

We will talk about molly fish care in this blog. We will also discuss the important factors such as their habitat, diet, aquarium parameters and health-care, etc.Everything that you need to know about Molly Fish care will be briefly discussed.


In this blog 

  • Key specifications of Molly fish
  • Why is molly fish care important?
  • Mollyfish
  • Molly fish Habitat
  • Molly fish Physical appearance and varieties
  • Molly fish tank set-up
  • Molly fish Diet
  • Molly fish health care
  • Molly fish care tips
  • Conclusion

How to take care of Molly Fish?

You can take care of your Molly fish by doing the following:

  • Get a spacious tank.
  • A spacious tank will give mollies the freedom to swim and hide in the tank and keeps them stress free.
  • Cycle the tank properly before introducing them in the tank.
  • De-chlorinate the tank
  • Water hardness and pH should be high.
  • Add high pH tolerant plants, They like planted tanks more.
  • Mollies themselves keep the tank clean by eating the algae, that grows due to rocks and driftwood in the tank
  • Temperature plays a great role for their growth and metabolism, so heaters and thermometers are mandatory in the tank to maintain the suitable temperature.
  • Some people do 50% water change water everyday for a week to remove excessive salt and keep the water quality intact by doing so.
  • Veggies should be boiled and cooled before giving to mollies.
  • Frozen food should be defrosted before feeding mollies.
  • Feed in small quantities twice or thrice a day.
  • Don’t overfeed,overfeeding can lead to constipation and accumulation of ammonia in the tank, which could be health hazardous.
  • Remove leftovers, don’t let them settle down in the tank.
  • If mollies are showing some illness symptoms, then give them a salt bath (1table tablespoon per 3 Gallons) for about 2-3 minutes and observe them if they are feeling better or not.
  • Seachem equilibrium can be used to increase the hardness of the water if they are kept in freshwater.
  • Check tank accessories if they are in working condition or not.
  • Separate the sick ones in a hospital tank to avoid its spread to the others in the tank.

Bi-weekly care tips for mollies

  • Water parameters are very important to monitor.
  • 15 % water changes several times a week for baby mollies.
  • Once a week water changes for adult mollies
  • Freeze-dried food should be given once or twice a week.
  • Always quarantine new fish for at least 2 weeks before introducing them in the main tank to avoid diseases.
  • Always clean the filters properly with the help of a good quality scrub to remove the waste from the tank.Clean filters can keep the health of the mollies well in the tank.
  • Clean tank decors and substrates weekly to avoid infections.

Key specifications of Molly fish

Binomial namePoecilia sphenops
HabitatNorth and south America
ShapeSize Color

Sexual dimorphism
Oblong body3.0-4.5 inchesSilver,BlackWild forms-light grayBreeding males- greenish-blueProminent
TemperamentPeaceful (specially black mollies) EasygoingCommunity friendlyBeginner friendlyMale mollies get aggressive during breeding season.
Care-levelEasy to raise
Tank sizeBest tank plant10-30 gallon aquariumVallisneria (tolerates high pH)
TemperaturepHWater hardnessSalinityLight72F-78F7.5-8.5 (slightly alkaline)20-30 KH (hardy species)HighAbundant
DietOmnivoresFerocious eatersAlgae eaterFeed small size food
LifespanBreeding cycle3-5 years in captivity3-5 weeks2-3 times a year they can give birth5-200 babies
No of species found40 species
Male to female ratio in the tank1:3 (1 male for every 3 female)1:5 (1 male for every 5 female)
Common namesShort finned molly
Molly diseaseShimmies

Why is molly fish care important?

Like any other fish even mollies are prone to get a wide range of diseases, if not given right care and hygienic environment by the owners.

They’re easy to keep and can adapt well in any setups.Though easy to handle,they are susceptible to bad water conditions if not maintained properly, and this can lead to a much shorter lifespan of  your little mollies.

So, it’s very important to know about each of them before introducing them into the aquariums.


Mollies are peaceful, easy-going, social, active and low-maintenance brackish water fish, currently 40 species in this genus are mollies except for the Endler’s.

They are livebearers like guppies and can give birth to live young ones directly into the water. They are a shoaling fish and will swim together as one unit.

Molly Fish Habitat

Their habitat in the wild can vary and have a wide natural distribution.The simple yet beautiful mollies are native to the America (majorly North and South America), and can easily adapt in different water conditions, from brackish waters to high hydrogen sulfide levels.

They are mostly found in warm and slow-moving tropical rivers with slightly alkaline pH.

Mollyfish Physical appearance and varieties

These fish are black all over but can come in different colors ,patterns, sizes and shapes, and most of them are very similar to the common molly  (Poecilia sphenops).

Sexual dimorphism is prominent in mollies, but for that they should reach the maturity age, as they dont display gender at an early age.Once they are mature, it becomes easy to differentiate the male and female mollies.

Shape and size of molly fish

  • Oblong body
  • Triangular-shaped head.
  • Tall in the middle and narrows towards the mouth.
  • Females (4.5 inches) are larger than males (3 inches)
  • Females have rounded bodies and a lumpy appearance while males have flat bodies.
  • Male mollies have brighter and bolder color patterns than female mollies.Female mollies dull colours.So male mollies are more attractive than female mollies.
  • Beautiful vibrant color patterns of males attract males for mating.
  • A caudal fin at the end which is like a large fan and can be transparent or colorful.
  • Male mollies have larger dorsal fins than females.
  • Anal fins are the most important part to identify the gender in mollies.Anal fins are lagrer in males than females.
  • Anal fins in males are specilized tube like structures call Gonopodium. Females anal fins are triangular shaped.

 Types or most common types of mollies

  • Sailfin Molly (Golden,Harlequin,large dorsal fin)
  • Platinum lyretail Molly (distinctive feature is their caudal fin)
  • Dalmatian Molly (Very popular in fish stores)
  • Balloon Molly (best among mollies to start over for the first time)
  • Gold Doubloon Molly (frequently purchased)

Molly fish tank set-up

A simple tank set-up is all they need with at least a 10-gallon aquarium. A 30-gallon tank is required by large mollies. 

A sandy substrate layer at the bottom of the tank and plants of your choice can also be introduced.

Taller plants like Anubias nana and shorter plants like Java fern can be a good choice for your mollies.Eel grass or vallisneria can tolerate the high pH and is one of the best choices for mollies tank.

Rocks, caves, and driftwood is used for decoration.Driftwoods are important for any aquarium set-up as they can develop algae for mollies to snack-on.

Molly fish water parameters

  • Water temperature: 72°F to 78°F (some species as high as 80 degrees)
  • pH levels: 7.5 to 8.5 (slightly alkaline)
  • Water hardness: 20 to 30 KH

Molly fish tank-mates

Mollies are peaceful fish and live happily if they are living with other peaceful species of similar size.

Selection of right tank-mates are very important in order to avoid fights in the aquarium.They usually get along well with most of the species except large fish and some cichlids.

Some suitable tank mates include:

  • Cherry barbs
  • Corydoras catfish
  • Celestial Pearl Danios
  • Dwarf gourami
  • Harlequin rasbora 
  • Bristlenose Pleco
  • Platies
  • Rosy Barbs
  • Tetras
  • Yo-yo loaches
  • Zebra Loach 

Fish to avoid includes:

  • Betta fish
  • Convict cichlids, except Angelfish

Molly Fish Diet

Mollies are not picky-eaters,and can be fed wide varieties of food from algae (essential part of their diet, and are also called as great algae eater), to green vegetables from your kitchen like lettuce, spinach, and zucchini,to prepared foods like spirulina flakes (once a day) and pellets,carotenoids(for pigmentation),live and frozen foods, etc. 

Avoid giving them dried foods, as they are mainly responsible for discolouration and health issues of mollies.

You can feed them small quantities of a balanced meal twice a day.A balanced nutrition can keep their gut healthy.

List of mollies food:

  • Algae
  • Vegetables (favorite)
  • Prepared food (Hikari micro wafers)
  • Live food
  • Frozen food
  • Carotenoid

Mollyfish health care

Molly disease, also known as the “shimmies” is the most common among them and it is due to poor water condition, ammonia spikes or extreme temperature changes.

They are even susceptible to Common freshwater diseases and can experience Ich, bacterial infections, flukes, and parasites.

Common signs and symptoms of molly disease

  • loss of appetite
  • Inactivity
  • Spots
  • Wounds
  • color changes
  • unable to swim properly
  • wiggle in one place 
  • constipation (affects balloon mollies)


Molly fish care is as easy as pie.These are low-maintenance fish and easy to care for.They are adaptable,easy-going,peaceful ,enchanting personalities and educational pets.

These qualities make them one the most beginner-friendly aquarium fish.

  • Grow well in big, spacious tanks
  • Friendly
  • Easy to care for
  • Livebearers
  • Eye-catching
  • Colorful
  • High spawning rate
  • Voracious eaters
  • Great algae eaters
  • Clean their own tanks
  • Dont news extra ordinary tank set-ups
  • Can tolerate any hardiness
  • Planted tanks are their favorites
  • High pH tolerant plants are best for them
  • Best beginner pet 

Frequently asked questions on molly fish care

Are mollies a good beginner fish?

They are one the most beginner-friendly aquarium fish.They are easy to maintain and you don’t need to know any rocket science to understand their behavior.

Are they aggressive?

They are peacemakers and are known for their happy and lively personalities, if kept with right tank-mates.They become aggressive only in the presence of male mollies, as they harass them during breeding season for mating and can cause stress in females.It’s better to keep less number of males in the tank to avoid such behavior.

What can be done to reduce the intensity of Molly disease?

The best way to reduce the intensity of disease in mollies is by monitoring the water conditions to check the rise in ammonia and nitrates levels weekly.Cleaning their tanks and checking up on their diets will definitely help them stay longer.

Can you keep 5-6 mollies together?

Mollies are a shoaling fish and will swim together as one unit.Groups of 4 or more can be kept together in 20-gallon tank.We can use even bigger tanks of 45-gallon to keep more mollies together in order to avoid clashes due to space.Smaller tanks won’t be a good idea for more number of mollies.