The Molly fish, also known simply as Molly, is a freshwater fish belonging to the Poeciliid family and is native to Mexico and Central America. It is a popular fish among aquarium enthusiasts for its colorful appearance, vitality, and ease of care.
Mollys are marketed in many countries as ornamental fish, and within the Molly category, three common species can be found: Black Molly (Poecilia sphenops), Sailfin Molly (Poecilia latipinna), and Veil Molly (Poecilia velifera).
In this comprehensive guide, we will tell you everything you need to know about the Molly fish: from the different types that exist to the specific care it requires, including tips for breeding and an ideal diet to maintain its health.
Characteristics of Molly Fish
Here is a technical sheet summarizing some general aspects of Molly fish breeding. However, it should be noted that some particular criteria are depending on the variety of Molly you are breeding.
- Common name: Molly, Mollyfish, Mollies, moli, or Mexican topote
- Scientific name: Poecilia sphenops (Black Molly), Poecilia latipinna (Sailfin Molly), Poecilia velifera (Yucatan Molly)
- Lifespan: 3 – 5 years
Molly Fish Species
Molly fish are available in different colors (orange, silver, black, green, gold), depending on the origin and sex. Some varieties are the result of crossing P. sphenops with P. latipinna; these two species easily crossbreed in the aquarium.
Black Molly Fish
The Black Molly or Black Molly (Poecilia sphenops) has a completely black coloration. It reaches maximum sizes of 6 cm; however, some varieties can reach 12 cm. The Black Molly is distributed from Colombia to Mexico, in freshwater and brackish waters.
Poecilia sphenops has a normal dorsal fin.
Sailfin Molly
The sailfin molly (Poecilia latipinna), also known as Molly Lira, is naturally distributed along the Mexican Atlantic coast and the southern United States, and can reach a size of 15 cm. It is characterized by males having a dorsal fin shaped like a sail, which is much more rectangular than common mollies.
Poecilia latipinna has 18 or 19 spiny rays in the dorsal fin, which males display like a fan. Sailfin mollies thrive best in brackish waters.
Sailfin mollies are the most visually appealing and come in many varieties with different color variations.
Mexican Sailfin Molly
Poecilia velifera, also known as the Mexican Sailfin Molly or Yucatan Molly, is endemic to the Yucatan Peninsula in Mexico. The giant sailfin molly is rarer and more challenging to breed.
The Mexican Sailfin Molly has a larger body shape, color, and dorsal fins in males, which makes them difficult to distinguish from the regular sailfin molly, but the fins of P. velifera differ slightly, having small spots.
The Yucatan Molly typically has a natural body color of green with dark spots, and there is also an albino variant.
How to distinguish Molly species?
Currently, nearly all mollies marketed for ornamental purposes are hybrids of the Black Molly (Poecilia sphenops), Sailfin Molly (Poecilia latipinna), and Mexican Sailfin Molly (Poecilia velifera) species.
Identifying wild varieties is simpler, and you can use the following criteria:
Fin size
The fin is one way to distinguish mollies. Molly fish are classified into two groups:
- Small fins: Includes the common molly.
- Large fins: Includes sailfin types.
Dorsal fin location
In sailfin mollies, the dorsal fin is situated in front of the anal fin, whereas in common mollies, this fin starts behind the anal fin.
Number of rays in the dorsal fin
This feature is used to distinguish sailfin mollies. P. latipinna has approximately 14 rays, while P. velifera will have around 18 rays.
Types of Molly Fish
There are over 20 different types of Molly fish, each with their own distinctive characteristics in terms of color, size, and fin shape. Some of the most popular types include:
- Dalmatian Molly: Dalmatian Mollies are known for their attractive black spots on a white or silver background, reminiscent of Dalmatian dogs. These fish are popular among aquarium enthusiasts due to their unique appearance and vibrant personality.
- Balloon Molly: One of the most popular varieties of Molly fish is the Balloon Molly, recognized for its distinctive rounded body shape. These fish come in a wide range of colors, including black, white, gold, silver, and many combinations thereof. Their distinctive silhouette makes them a striking addition to any community aquarium.
How to breed Molly fish?
Mollys are livebearers and highly prolific. Furthermore, males and females are easy to distinguish, with the male being smaller and having a gonopodium, which is the reproductive organ. These fish start reproducing at the age of 4 months (Divya, 2018); thus, you should have a population of female and male breeding-age Molly fish.
Breeding Mollys is straightforward, provided they are provided with the right conditions. Rasanjalee and Dissanayake (2019) recommend a ratio of 3 females to every 2 males to avoid fights and prevent females from being harassed; additionally, vegetation should be included.
It is worth noting that research by Schlupp et al (2010) found that female common mollys (P. sphenops) preferred male mollies with filaments on their faces resembling a mustache. The researchers suggest that this “mustache” on the male molly could transmit tactile signals to the female molly.
Another curious aspect, according to Palmer and Hankison (2015), is that the wavelength of ultraviolet light appears to influence the female of the Sailfin Molly (P. latipinna) in choosing the male molly; therefore, you should be careful in choosing the lighting for your aquarium.
The male molly fertilizes the female internally using its gonopodium. In this regard, it is important to note that Scherer et al (2018) concluded that the size of the male molly fish influences reproductive success, resulting in more offspring; however, it does not affect the quality of the larvae.
The female molly is capable of storing sperm from a single mating to produce up to nine broods. Pregnant mollies are recognized by a black spot positioned anterior to the anal fin.
The molly female produces 20 to 150 larvae measuring 1-12 mm in length after six to eight weeks of gestation, depending on the temperature. It is important to separate the pregnant female into a separate tank, as adult mollies prey on the offspring.
Durgude et al (2020) determined that for molly cultivation in cages, aiming to achieve the highest fry production rate, the most appropriate density is 50 fish/m2 in a sex ratio of 4 females to 1 male over 90 days.
Molly Fish Care
The mollyfish is a hardy species and adaptable to different water conditions. However, for it to thrive in your aquarium, it is important to provide it with the proper care:
- Aquarium size: The ideal aquarium or fish tank size for Molly fish (one male and three females) is at least 40 liters. For Sailfin Mollys, aquariums of at least 100 liters are required.
- Water parameters: The ideal water pH is between 7 and 8, hardness between 10 and 20 dGH, and temperature between 24 and 28°C.
- Water changes: Frequent water changes should be performed, at least weekly, accompanied by siphoning, in amounts equal to 30 to 40 percent of the aquarium’s capacity.
- Decoration: You can decorate the aquarium with plants, rocks, and other decorative elements. Plants that can be planted in the Molly fish tank include Elodea, Ambulia, Limnophila sessiliflora, Vallisnerias, Didiplis diandra, Ludwigia repens, among others. The aquarium should mimic the natural habitat of Molly fish, which will reduce stress for the fish.
- Social behavior: Molly fish are peaceful and can coexist with other species of freshwater fish.
- Lighting: Zutshi and Singh (2021) determined that a long-day photoperiod (18 hours of light and 06 hours of darkness) was effective in improving skin color in P. sphenops without measurable stress or mortality.
Selective Breeding of Molly Fish
Most of the mollies available in the ornamental fish trade were obtained through selective breeding and are hybrids.
Over all these years of selective breeding, a variety of colors and patterns have been produced, ranging from black molly, dalmatian molly, orange molly, etc. The albino coloration comes from the sailfin species.
Body shapes and fins have also been selectively bred. Molly fish now have a more robust body shape, lyre tails, among other characteristics.
The most frequent crosses occur between P. sphenops and P. latipinna, resulting in lyretail, moon, and flagtail fish.
A unique variety is the Balloon Molly. This fish has a short, round shape. Breeding causes an unnatural curvature of the spine. However, this shape causes great harm to internal organs.
What do Mollyfish eat?
Molly fish are omnivorous and feed on a wide variety of foods. An ideal diet for these fish should include:
- Commercial Molly fish foods: These foods contain all the nutrients that fish need to stay healthy. Sharma and Garg (2023) found that including 3% earthworm flour (Eisenia fetida) in the diet of Molly fish breeders (P. sphenops) may favor seed production.
- Live foods: You can offer your Molly fish live foods such as brine shrimp, daphnia, and bloodworms.
- Vegetables: You can offer your Molly fish vegetables such as lettuce, spinach, and zucchini.
It is important to feed Molly fish a varied and balanced diet to maintain their health. The recommended feeding frequency for Molly fish is 2 to 3 times per day, with small amounts of food given each time.
Technical criteria for feeding Molly fish
If you keep some Molly fish in your tank, they will accept any type of food: live, dried, flakes, etc.; however, for a balanced diet, a source of plant-based food is necessary.
Feeding Molly fish fry (larvae – fry) consists of dried food and small water fleas, brine shrimp nauplii (Artemia), tubifex or bloodworms. Regarding this, Sumithra et al (2014) reported that a mixed diet (rotifers, cladocerans, and copepods) is suitable for achieving high growth and survival rates in Molly fish larvae.
A practice that is becoming widespread is the use of probiotics in fish feeding. Ahmadifard et al (2019) determined that using Artemia enriched with Bacillus subtilis (1 x 105 CFU/mL) improves reproductive parameters, intestinal microflora, and resistance to pathogenic bacteria in Sailfin Molly (Poecilia latipinna).
Pour et al (2014) recommend supplementing Molly fish artificial diets with garlic (15 g/kg) to improve growth performance, feed utilization, and body composition. Likewise, Gamit et al., (2022) recommend the inclusion of rose flour in the diet of Poecilia sphenops Molly fish improves growth and coloration.
Molly fish behavior
Molly fish have peaceful and sociable behavior with other fish; however, adult males can become territorial with other aquarium fish, which is the main reason why Molly fish can show aggressive behavior towards other species of ornamental fish.
Molly fish are suitable for a community aquarium and are suitable for breeding with guppies, platies, and swordtails.
Diseases affecting Molly fish
Molly fish appear to have lower resistance to infections from fungi or ciliates like Ichthyophthirius multifiliis (Ich), compared to other fish. Fungal and ciliate infections can be prevented and treated by adding 1 to 1.5 teaspoons of salt (iodine-free) to the aquarium. Maceda and Cable (2014) found that baths in sea salt (10 g/L) were more effective against Ich.
Another common disease is the so-called “Molly disease,” caused by the bacterium Flavobacterium columnare, which causes deformity in the fish’s spine.
Molly fish are subject to the same diseases as other tropical fish. The best way to prevent a disease is to provide your Molly fish with the right environment and a well-balanced diet.
Tips for Molly fish care
- Wan et al. (2014) discovered that Molly fish can be cultivated in brackish water (3 to 6 PSU).
- Valencia et al (2016) in their research concluded that the growth of Molly fish fry is favored in the presence of salt, recommending marine salt concentrations of 13‰ for black molly and 18‰ for Sailfin Molly.
- Prada and Velmurugan (2020) concluded that the photoperiod is an essential factor in improving the color of P. sphenops; however, the orange balloon molly develops chronic stress when continuously exposed to LED lights.
- Sailfin Molly (P. latipinna) larvae grow best in white light under a photoperiod of 12 hours light and 12 hours darkness (Shahbazi et al., 2018).
Conclusion
The Molly fish is an excellent choice for beginners and aquarium enthusiasts. It is a colorful, hardy fish that is easy to care for. With proper care, Molly fish can live up to 4 years in your aquarium. If you are just starting out in ornamental fish breeding, Molly fish are definitely for you. These fish require only basic care and can be the start of a very exciting hobby.
Mollyfish females and males are highly prolific as long as you provide them with the appropriate conditions for breeding.
References
Animal-World. Pet and animal information.
Ahmadifard, N., Rezaei Aminlooi, V., Tukmechi, A. et al. Evaluation of the Impacts of Long-Term Enriched Artemia with Bacillus subtilis on Growth Performance, Reproduction, Intestinal Microflora, and Resistance to Aeromonas hydrophila of Ornamental Fish Poecilia latipinna. Probiotics & Antimicro. Prot. 11, 957–965 (2019). https://doi.org/10.1007/s12602-018-9453-4
Divya D. 2018. Study on breeding behavior in ornamental fish, Poecilia sphenops. IJRTI | Volume 3, Issue 8 | ISSN: 2456-3315
Durgude A., Dabir Pathan, Nikhil S Sawant, Pankaj Patil and Gauri Shelar. 2020. Effect of stocking densities on reproductive performance of black molly, Poecilia sphenops in cages. Journal of Entomology and Zoology Studies 2020; 8(3): 2019-2023.
Gamit SA, Kapila Manoj, Bengani R, Gamit DN, Lende SR, Vasava RJ, Solanki VK, Vadher DR and Mevada JN. Comparision of growth and colour enhancement in Poecilia sphenops using different carotenoid supplements. The Pharma Innovation Journal. 2022; 11(11S): 1943-1946.
Maceda A. and J. Cable. 2014. Efficacy of sea salt, metronidazole and formalin-malachite greens baths in treating Ichthyophthirius multifiliis infections of mollies (Poecilia sphenops). Bull. Eur. Ass. Fish Pathol., 34(5).
Palmer M. and S. Hankison. 2015. Use of ultraviolet cues in female mate preference in the sailfin molly, Poecilia latipinna. acta ethol (2015) 18:153–160 DOI 10.1007/s10211-014-0195-3
Pour, F.; Maniat, M.; Vahedasl, A.; Ghayem, S. 2014. Enhancement of growth performance and body composition in molly fish (Poecilia sphenops) associated with dietary intake of garlic (Allium sativum). International Journal of Biosciences (IJB) 2014 Vol.5 No.8 pp.115-121 ref.26
Prada M. and K. Velmurugan. 2020. Effects of artificial photoperiod on the body colouration in the ornamental fish Poecilia sphenops. Kongunadu Research Journal, 7(1), 69-75. https://doi.org/10.26524/krj.2020.11
Ramos A. . Poecilia sphenops (Valenciennes, 1846). Atlas PlanetAcuario
Rasanjalee S., y C. Dissanayake. 2019. Effects of culture conditions on growth and survival of Poecilia sphenops and Poecilia reticulata. Int. J. Aquat. Biol. (2019) 7(4): 202-210
Shahbazi Naserabad, S., Ghafari Farsani, H., Abedi, M., Rashidiyan, G. The effect of different colors of light on growth of Molly fish (Poecilia latipinna). , 2018; 5(4): 177-184.
Sharma, K., Garg, V.K. Utilization of vermi-incorporated feed for the seed production of two freshwater ornamental fish, Xiphophorus helleri and Poecilia sphenops. Biomass Conv. Bioref. (2023). https://doi.org/10.1007/s13399-023-04955-7
Scherer, U., Tiedemann, R. & Schlupp, I. Male size, not female preferences influence female reproductive success in a poeciliid fish (Poecilia latipinna): a combined behavioural/genetic approach. BMC Res Notes 11, 364 (2018). https://doi.org/10.1186/s13104-018-3487-2
Schlupp, I., Riesch, R., Tobler, M. et al. A novel, sexually selected trait in poeciliid fishes: female preference for mustache-like, rostral filaments in male Poecilia sphenops . Behav Ecol Sociobiol 64, 1849–1855 (2010). https://doi.org/10.1007/s00265-010-0996-y
Sharma, K., Garg, V.K. Utilization of vermi-incorporated feed for the seed production of two freshwater ornamental fish, Xiphophorus helleri and Poecilia sphenops. Biomass Conv. Bioref. (2023). https://doi.org/10.1007/s13399-023-04955-7
Sumithra V., A. Janakiraman, K. Altaff. 2014. Influence of Different Type of Feeds on Growth Performance in Black Molly, Poecilia sphenops. International Journal of Fisheries and Aquatic Studies 2014; 1(6): 24-26
Trujillo-Jiménez Patricia, Toledo Beto Héctor. Alimentación de los peces dulceacuícolas tropicales Heterandria bimaculata y Poecilia sphenops (Cyprinidontiformes: Poeciliidae). Rev. biol. trop [Internet]. 2007 June [cited 2021 Nov 04] ; 55( 2 ): 603-615. Available from:
Valencia M., H. Molina, E. Manga, M. López, A. Fernández, E. Vázquez. 2016. La salinidad como modulador del crecimiento en los peces de ornato Poecilia sphenops y Poecilia latipinna (Pisces: Poeciliidae). Revista Latinoamericana el Ambiente y las Ciencias 7(15): 101-120 2016
Wan N. W. H. Husna, Annie Christianus, Zaidi C. Cob, A. Ghaffar Mazlan, K. Das Simon. 2014. Effects of salinity and water quality parameters on the breeding and larva rearing of black molly Poecilia sphenops in laboratory condition. Aquaculture, Aquarium, Conservation & Legislation; Cluj-Napoca Tomo 7, N.º 1, (Feb 2014): 8-14.
Zutshi, B., Singh, A. Impact of Photoperiod as an Environmental Cue on Growth and Reproductive Performance in the Red Eyed Orange Molly (Poecilia sphenops). Proc Zool Soc 73, 25–31 (2020). https://doi.org/10.1007/s12595-019-00294-6
Zutshi, B., & Singh, A. (2021). Artificial photoperiod influence on survivability, pigmentation and hematological parameters in live-bearer ornamental fish, Poecilia sphenops. Indian Journal of Ecology, 48(2), 508-512.
