The name says it all – when you read the name “molly fish,” you instantly picture an adorable, beautiful little fish.
And as the name implies, this fish is the true star of the aquarium. Most people have heard of the molly fish, as it is one of the most popular fish species kept by aquarium hobbyists. Both easy to care for and easy to include with other species of fish, the molly fish is an active, peaceful fish that offers plenty of activity and unique behaviors for you to enjoy watching in your tank.
Before you get started with raising this enjoyable fish, there are a few things you need to know. First, the molly family includes a wide variety of fish, with each varying in shape, size, and colors. Despite these differences, the main thing you need to know is that mollies are delightful fish that you can care for with just a little bit of background knowledge.
We will tell you everything you need to know in our convenient guide to raising the molly fish.
Molly Fish Background
Molly fish are frequently referred to simply as mollies – so if you hear the latter name being used, don’t get confused! This freshwater fish is a member of the Poecilia genus and the Poeciliidae family. With the exception of the Endler’s livebearer, all fish in this genus are molly fish. There are a whopping 39 different species of mollies, in fact!
All of these fish are native to North, Central, and South America, but they can inhabit a wide range of habitats. In the wild, these fish are normally found in shallow streams and rivers in South and North America. They prefer bodies of water that contain a sandy or rocky substrate, but they can tolerate a range of water conditions. They are well suited to brackish bodies of water as well as those that have high quantities of hydrogen sulfide.
They prefer well-planted areas. Plants are used as an important source of shelter, as well as a breeding site. Because molly fish tend to live in warm, tropical and subtropical areas, there is usually plenty of sunlight and warmth to allow these plants to thrive.
In general, the water in which molly fish are found are both warm and possess minimal water flow or current. The pH will vary depending on the habitat, but is usually somewhat alkaline in nature.
Mollies are popular species for raising in an aquarium because they are hardy and resilient to most common aquarium-related challenges. They can adapt well to most community settings, and when raised in the proper conditions, can live up to five years!
Most aquarium and pet stores sell molly fish, as they are arguably the most popular species of freshwater fish. They are relatively inexpensive, with most species and varieties costing only $2 to $3 apiece. Therefore, it’s quite affordable to quickly fill your tank with lots of mollies!
Molly Fish Appearance And Behavior
There are plenty of varieties of molly fish from which you can choose. Most are similar in appearance and behavior to the common molly, but you will notice differences in patterns, colors, shapes, and sizes among each.
Most mollies will have flat bodies that are taller in the middle and narrow at the mouth. At the other end of the body, the fish will have a large, fan-shaped caudal fin. This fin can be either colorful or completely transparent. You might also see the dorsal fin raised as a fan, like the caudal fin, or it can lie flat against the body.
There are various differences between the genders of these fish that make them easy to breed. Females, for instance, will have anal fins that spread out into a fan shape, while the males will have a pointy anal fin. Females will grow to larger sizes on average – usually reaching around four inches in length – while males will remain smaller at three inches. A pregnant female is even easier to spot, as her belly will noticeably swell.
Beyond these basic differences, there are some other key differences between individual species. While all molly fish are completely black, there are some that have different patterns and colors. The sailfin molly, for example, comes in a range of colors. However, it is distinct from other fish in that it has a large, tall dorsal fin that extend from the back of the head to the start of the caudal fin. The lyre tail molly, on the other hand, has a narrow, pointed caudal fin that trails behind it.
Your choices in molly fish don’t end here, though – you can also choose to raise red, balloon, Dalmatian, or even orange molly fish.
Molly fish are very peaceful but occasionally show signs of aggression. These signs usually appear when your fish are crowded or when the tank is filled with lots of other aggressive inhabitants. To prevent this, make sure your tank is large and has plenty of hiding spaces. You should also take care in selecting appropriate tank mates for your molly fish.
These fish are extremely active and will produce a vibrant show of color when they are kept in large groups. This is because molly fish are schooling species. You should include plenty of mollies in your tank to encourage shoaling behaviors. Make sure your groups are composed mostly of female molly fish, as too many males or an improper ratio can cause stress to your females as the males will harass them.
It’s fascinating to watch a group of mollies because they each have unique behaviors. You can easily see the different personalities among the active members of your groups. This makes it quite easy for you to get attached to your new fish!
Molly Fish Tank And Water Requirements
Mollies are frequently bred for the aquarium trade, so they are well adapted to most tank settings. You won’t need to modify your tank in many ways in order to suit these flexible, hardy fish. However, there are some general conditions you will need to maintain in order to keep your fish both happy and healthy.
Start by placing a thick layer of sandy substrate along the bottom of your tank. Your fish won’t spend a large amount of time down here, but the fine grains will make it easier for you to support plant life – which is an absolutely necessity if you are raising molly fish.
You can choose just about any kind of plants for your aquarium, but try to select those that will work well with your other fish (if you have any) in addition to your molly fish. Tall plants are a good option, as they will provide adequate shelter and hiding places for mollies, who tend to swim in the center of the water column. You might want to consider plants like Anubias nana, for example.
It would be wise to include other types of decorations, too, which will provide lots of hiding spaces for fish who are being harassed by other tankmates. You can use items like rocks to establish crevices and caves for your fish to get away – just make sure any decorations you add to your tank are cleaned thoroughly to prevent the accidental introduction of bacteria or parasites to the tank.
Your tropical fish tank should be nice and warm to keep your fish healthy. Try to maintain temperatures of around 71 to 79 degrees Fahrenheit. The pH should be maintained between 6.7 and 8.5 and the hardness between 20 and 30 KH. You can maintain a slightly brackish tank if you so desire, but it will limit the fish that you can keep successfully in this environment.
Typical aquarium lighting will be plenty sufficient for your mollies. You need no other equipment, like an air or water pump, either. Because mollies are adapted to slow-moving waters, you don’t need to go to special lengths to keep them comfortable.
Keep in mind, however, that although these fish are small, they need plenty of space to swim about. It is generally recommended that you keep a molly fish in a tank that is at least 10 gallons in volume. Larger mollies may require slightly larger tanks of at least 30 gallons, but keep in mind that no tank is really too large and it’s better to err on the larger side of things. Remember, each additional molly that you place in the tank will need another three gallons to live comfortably.
What Do Molly Fish Eat?
There are plenty of foods you can choose to feed your mollies, as they are omnivores. In the wild, these fish usually snack on plants and algae, with the occasional small invertebrate thrown in. In your home’s fish tank, you can provide them with similar foods. Just make sure it is incredibly varied.
Mollies are unique in that they are one of the most popular algae eaters you can find for your tank. They will use their lips to scrape algae from the surface of the glass. Vegetation is important, so you should take extra care to give your mollies plenty of vegetables, which will provide all the nutrients and minerals that they need to stay healthy.
Try to provide varied sources of vegetables, like lettuce, zucchini, spinach, or even broccoli. You can feed these fresh or frozen, but make sure they are chopped into small pieces so that they are easy to digest for your mollies.
If you don’t want to feed these sorts of foods, you can choose to feed artificial foods that you can buy at the store. Popular choices include pellets and flakes. These should be the cornerstone of your molly’s diet, but you can add other supplemental foods like live and frozen foods to make up for any nutritional gaps or deficiencies.
Foods like bloodworms and brine shrimp are excellent sources of protein. Live foods are chock full of nutrients and it’s also quite enjoyable to watch your mollies interact with live foods! THey will spend a great amount of time chasing these live foods around the tank. Frozen sources of protein are also acceptable.
When you feed your mollies, make sure you never feed more than they can eat within two minutes. Feeding in excessive quantities will only come back to bite you. The digestive system of your fish will not have time to catch up, and your fish will be overwhelmed by all the food. Much of the leftover food will end up as algae.
Molly Fish Tank Mates
Many people choose to raise mollies because they are so compatible with other tank mates. You can place them in just about any tank, and they will get along with the inhabitants with ease. However, some good choices to consider include tetras, barbs, catfish, danios, gouramis, rasboras, platies, and loaches. Generally, any small peaceful fish will make a suitable companion.
You should avoid large fish species, as well as those that are aggressive. Large, aggressive species will have a natural inclination to prey upon your mollies. Even if they don’t, it’s likely that they will chase your mollies to the point of stress. This stress can lead to accidental injury or even death.
One species to avoid is the cichlid. This species has plenty of individuals who can harm your mollies. Convict cichlids, for example, are very aggressive. They will go after your mollies and harass them endlessly. Angelfish, though, are one cichlid species that can get along just fine with your mollies.
You can even include other non-fish species with your mollies. Invertebrates are usually a good choice, because they will be largely ignored by your mollies. You can add snails and shrimp to your molly tank to create a more diverse community. Many of these invertebrates eat algae, helping to keep your tank clean at the same time!
Because they are shoaling species, it’s always a good idea to keep mollies in groups of at least four or more. These fish naturally congregate together, and it’s important that you have multiple fish in case the males begin to harass the females. This will help distribute some of this pressure and i will make it easier for females to get away and avoid being continuously bullied.
Common Molly Fish Diseases
Mollies are well adapted to living in captivity, and therefore are not susceptible to many diseases. Keeping a clean, well-maintained tank with stable water conditions is the easiest way to prevent and treat disease in a freshwater environment. Make sure your nitrites and ammonia remain at 0 ppm.
The most common disease to affect molly fish is actually known as molly disease. It is commonly referred to as shimmies or livebearer disease as well. This is caused by poor water quality and may cause your fish to become inactive. They might wiggle or remain in one spot. This can be remedied by adjusting your water parameters and cleaning out any toxins that might be present.
Mollies are susceptible to other diseases that can affect freshwater species, too. You might notice that your fish have issues such as ich, velvet, and dropsy. These can cause symptoms ranging from a loss of appetite, a reduction in activity, or a change in colors. Again, carefully monitoring the quality of your fish’s diet as well as the water quality can help reduce any and mitigate any potential problems.
Breeding And Life Spans Of Molly Fish
Many people choose to raise mollies because they are so easy to breed. As livebearers, these fish develop their eggs inside their bodies – this results in the birth of live fry instead of the depositing of eggs on surfaces in the tank. Mollies are one of the easiest species of fish to breed in captivity, as they mate on a regular basis.
If you are considering breeding your molly fish, make sure they are housed in a separate breeding tank with immaculate water quality. You might want to raise the temperature slightly to encourage the initial mating process, but whatever you do, don’t raise the temperature higher than 78 degrees.
When your fish are ready to breed, the males will begin the process. They will perform elaborate mating displays in which they attempt to court the females. When the females are ready, they will allow the male to fertilize their eggs. Females usually choose to mate with the largest males, but sometimes males will sneakily creep up behind a female to fertilize her eggs without her realizing it at first.
Once the eggs are fertilized, it takes most females about 40 days to release her young. Depending on the size of the female, the quantity of fry will also vary. Most release up to 100 young fry.
When your fry are born, you need to make sure they are separated from the adults. Otherwise, they can be eaten. To avoid this, place the pregnant mollies in a breeder box just before they are due to give birth. The young can leave the box via small holes, but the adults cannot. You can feed fry foods like small flakes or pellets until they are large enough to eat the same food as their parents. Then, they can be introduced to the regular tank.