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molly fish care guide

Molly fish are typically among the coolest aquarium fish around. These types of fish are referred to as livebearers (like platies and guppies).

In essence, what makes these particular fish remarkably cool is that they exist in such a flurry of numerous varying color variants. You can choose from a wide array of colourful molly fish, including yellows, oranges, whites, blacks, fancy tailed, balloon belly, and so much MORE!

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Orange Molly FishOrange Molly Fish


Molly fish, or commonly known in simple terms as "mollies" are freshwater fish distinctly coming from the Poecilia genus in the overall Poeciliidae family. Every species in this particular genus are typically mollies except for the Endler’s livebearer. Currently, this genus boasts 40 species, with 39 being mollies. Essentially, these groups of fish are American natives, although their habitats usually vary significantly.

What is perhaps interesting about mollies in the fact that similar to guppies, mollies are livebearers. What this means is that they usually hold their eggs within their bodies right until they eventually give birth to their young ones directly into the water.

Mollies are quite a popular fish group. Most of the species are easy to take care of and quite hardy, which renders them a fantastic option for any beginner — also, these fish work particularly well in serene community aquariums. If you keep them in a healthy setting, mollies will effectively thrive and may live up to around five years.

Such is their popularity that it is rare to find a fish store that does not usually sell mollies. Typically, there are among the most popular shoal of freshwater fish. If you are looking to start an aquarium with these fish, you can find the common varieties for an affordable price of between $2 and $4 for every fish, although some rare species may cost a little more.

Molly Fish Behaviour

Mollies are usually a uniquely peaceful group of fish, although they can exhibit behaviours of aggression either when crowded or subsequently surrounded by hostile tank mates. As such, it is vital that they are placed in an adequately big tank, as well as ensuring they co-exist with suitable tank mates.

These fish are social and active and therefore delight in schooling together. Mostly a shoal of these fish must be primarily female because males are naturally known to stress and harass females.

Usually, it is quite easy to identify personalities in various active fish like mollies. If you watch them for a while you will notice, that every molly fish behaves differently from each other. 

Female Spotted Molly FishFemale Spotted Molly Fish

Molly Fish Types


Naturally, there are numerous varieties of molly fish, with most of them being relatively similar to the otherwise popular molly Poecilia sphenops. However, what sets them apart are various elements such as patterns and colors, although shapes and sizes may also vary too.

The most common type of molly boasts a distinctively flattened body. The fish is tall in the middle section and proceeds to narrow towards a distinct point at its mouth. On the other end, this fish boasts a caudal fin that is ideally a massive fan, which is usually either colorful or transparent. It can raise its dorsal fin as a typical fan, similar to the caudal fin, or, subsequently, flatten it against its body.

When it comes to mating, molly fish is remarkably quite easy to mate. Naturally, the female molly fish feature an anal fin that effectively spreads into a distinct fan. As for the males, they have a more pointed anal fin. Male molly fish-tails can grow to about 3 inches, while for the females, they have a relatively long one that can potentially reach about 4.5 inches.

For the latter, pregnant females usually look even bigger. Generally, their bellies often swell, subsequently getting bigger in comparison to the other females.

Below is an outline of several popular molly fish species suitable for typical home aquariums:

  • Lyre-Tail Molly: Similar to the aforementioned sail-fin mollies, the lyre-tails effectively stand out courtesy of their fins, although this is basically their caudal fins. Both the bottom and top of their fins narrow naturally into points that trail behind the remaining section of the fish.
  •  Black Molly Fish: Typically these species are usually wholly black. Besides this - these fish are nonetheless similar to the popular molly.

  • Sail-Fin Molly: Molly fish that are bred in numerous different patterns and colors. Their most prominent feature is undoubtedly their large dorsal fin that is taller and usually runs from behind their heads to merely before their caudal fins. Some other popular molly fish species include Red, Dalmatian, Orange, Balloon, and White Molly Fish.
Lyre Tail Molly FishLyre Tail Molly Fish

Molly Fish Tank Set Up

Ideal Habitat And Tank Conditions:

Generally, the habitat of a molly can significantly vary, especially when they are in the wild. Mollies have typically adapted to numerous different provisions of water conditions. This is inclusive of their distinct tolerance to high levels of hydrogen sulfide, as well as brackish waters.

Mollies are primarily found within the shallow streams and rivers across South and North America. As such, when setting up a fish tank, the substrates in these spots should be sandy, boasting debris and rocks on top. It also needs to comprise plenty of plants as they usually utilize that as their shelter, although they also play a significant role in reproduction.

Furthermore, since the rivers are found in exclusive tropical climates, you also need to ensure you provide an ample supply of light to promote plant growth. Finally, the water needs to be slow-moving and warm, with the pH being a little alkaline. Naturally, molly fish that are bred for typical aquarium purposes are all adapted to similar settings, and you, therefore, need not worry about each molly fish variety requiring a different tank set up.

 A sandy substrate layer along your fish tank’s bottom is an excellent idea. Although they usually won't spend a lot of time down at these particular levels, this fine-grain substrate are ideal for keeping and growing plants.

Ideal Temperature And P H:

This type of tropical fish requires a heater inside the tank to maintain the temperature between 72 and 78 0 F. Maintain the hardness between 20- 30 KH and pH between 6.7 and 8.5. 75 – 80 0 F is usually the recommended temperature for mollies.

This is because it is indigenous in tropical areas of the world. The pH is supposed to be between 7 and 8, and it is recommended to utilize driftwood inside the aquarium because it is known to reduce the pH value. Moreover, the aquarium for mollies should have ample open space for swimming, and should also be decorated.

Molly fish are referred to as brackish water fish – saltwater combined with freshwater, although the ration of saltwater should be small. If you add water to your freshwater, it helps out with bacteria, although if there are any freshwater friends in there, it makes it challenging to pour salt in the water and mix the water up to make the mollies more comfortable.

Mollies will be okay in freshwater, and you can add small quantities of salt. Some individuals recommend relatively brackish waters for the mollies. There are no confirmed benefits for this, and it reduces the mates you can have in the aquarium. Standard lighting in the aquarium is enough. It is not necessary to have additional equipment.

Black Molly FishBlack Molly Fish

What is the ideal tank size needed?

A molly fish requires no less than a 10-gallon aquarium. This size will accommodate up to four molly fish depending on the species – bigger mollies such as the sail-fins will require an aquarium of at least 30 gallons. Every extra molly will need approximately 3 gallons to exist comfortably.

Molly Fish Tank Mates

Mollies are peaceful fish, and they do not cause many issues within the tank - thus, they live well with other species. Some ideal choices are zebra loaches, cherry barbs, Danios, Yo-yo loaches, Corydoras Catfish, Rosy Barbs, Platies, Dwarf Gouramis and Tetras

The fish to avoid are big or aggressive ones. Large fish will attempt to eat the mollies, and the aggressive ones may stress them to the point of death. Cichlids are among these bad examples.

Many invertebrates will be comfortable living with the mollies since they will be ignored most of the time. Snails and shrimps are a great choice, and there are lots of species of these to choose from.

Balloon Molly FishBalloon Molly Fish

Molly Fish Feeding

Since molly fish are omnivorous, there are numerous different types of foods that you can subsequently feed them. While in the wild, they usually eat small invertebrates, although it is mainly algae and plants. You can also offer them various similar foods in the aquarium.

Naturally, algae constitute a significant part of the molly fish diet, and they utilize their lips to scrape the algae from various surfaces. Also, vegetation is quite essential. You can feed them small pieces of some green veggies from the kitchen. Spinach, lettuce, and even zucchini are among the recommended options you can drop into the aquarium.

What's more, you can also use them in making your unique homemade food for the fish. Some artificial foods, such as pellets and flakes, can also be another easy alternative. You can try supplementing these with some other foods to provide the fish with a wide array of essential nutrients.

Frozen and live foods are distinct protein sources. Brine shrimp and bloodworms are a fantastic choice, although most other alternatives can also work quite well. As for live foods,they are a rather interesting food option for your fish when it comes to their feeding time.

When it comes to feeding molly fish, ensure that you feed them relatively small amounts two times a day. Offer them as much as they can finish within 1 - 2 minutes.

Molly Fish Care Guide

As earlier mentioned, molly fish are among the more adaptable and hardy fish species in the world. Like with any type of fish, the most critical factor when it comes to fish care is ensuring that you place them in a clean and well maintained aquarium. What's more, you should know how to care for your fish tank effectively.

Typically, this can include continually monitoring the water conditions as well as checking that the nitrites and ammonia levels are effectively at 0 ppm.

Typically, your mollies might develop a condition known as 'molly disease' or 'shimmies,' or 'livebearer disease.' Nonetheless, this particular condition is not necessarily a disease since it comes when the conditions of the water are inadequate. In the event that your fish have this condition, you will notice that the affected fish swim around relatively less than usual, while also shimmying and wiggling in one given spot.

On such occasion, ensure that you check your various water parameters and subsequently rectify any concerns. Once the conditions get back to normality, you should eventually see noticeable improvements in the overall health of your molly fish.

Besides molly disease, your mollies can also be susceptible to a wide array of common conditions that are frequently observed in numerous freshwater fish like velvet or white spot.

Ensure that you keep a close eye on your mollies to identify any signs of disease. Some of the most common symptoms you should watch out for include inactivity, color changes, appetite loss, wounds, or even spots.

By properly cleaning the fish tank as well as switching their diets, you can quickly decrease the severity of the diseases. Nonetheless, if even after taking these simple actions, the condition still persists with the affected fish, you can decide to visit various certified stores, or search online and purchase the different appropriate treatments.

How To Breed Molly Fish

Generally all molly fish are live-bearers. This is to means that their eggs usually develop within their bodies to facilitate the release of live fry.

Also, mollies rank among the most comfortable groups of fish to take care of and breed in captivity, and depending on the conditions; they will usually mate quite regularly.

Nonetheless, the fish tank conditions must be ideal for facilitating breeding. Both the tank and the water, of course, need to be clean.

To help initiate the process of mating, you can slightly raise the temperatures, although you should be careful not to go over 78°F. The male mollies perform an exclusive courting display for their female counterparts, and when the females are ready for mating, they will usually allow the males to fertilize their eggs.

On some occasions, though, the male mollies often attempt something called 'sneak copulation.' This is when a male molly fish approaches an unaware female molly from behind.

Naturally, female mollies often choose to mate with the largest mollies. Usually, after the fertilization has occurred, it takes between 35 and 45 days before the release of the young fry. The larger female mollies can release up to 100 juveniles.

When the young mollies are released, you need to separate them from the other adult fish, or they will subsequently be eaten. Due to this, one of the options you can go for is putting the otherwise pregnant mollies in an exclusive breeder's box just before they give birth. This box has small holes that allow the young to freely exit the box while their adult mothers remain trapped in the box.

For the young, you can usually feed them various foods such as broken flake food. This is until they are grown enough to consume the same foods as the adults, after which you can proceed to mix them in with the adults.

Female Gold Molly FishFemale Gold Molly Fish


In essence, the unique and harmonious character of the mollies means that there are very few reasons if any, why you should not get yourself some molly fish. They are an excellent option when it comes to community aquariums.

All you need to do is assess whether you have suitable tank mates. Be sure to avoid the more aggressive or large fish species.

What's more, their overall health and well-being are dependent on the distinct fish tank conditions that effectively suit their ideally preferred range.

Fundamentally, mollies can tolerate an extensive range of water parameters, and therefore can fit in a wide array of different fish aquariums. Furthermore their diet will not give you any problems. Molly fish can consume an extensive array of different types of foods.

In general, mollies are quite easy to take care of, provided you have the ideal fish tankUltimately, you get an exciting species of fish that are not only easily bred, but that also exhibit numerous different colors and display a great deal of activity.

Happy Fish Keeping.

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