Etymology
The genus Nematobrycon derives its name from the Ancient Greek words νῆμα (nêma) and βρύκω (brúkhō). The former refers to the elongated thread-like rays present in the caudal fin of species belonging to this genus, while the latter originally denoted the possession of fully-toothed maxillae in the mouth. However, the latter term has since been associated with the generic names of many characiform species to indicate their presumed kinship.
The specific epithet, lacortei, is named after Rosario LaCorte, an aquarist who has contributed significantly to the field of ichthyology. His dedication to the study and breeding of aquarium fish has helped advance our understanding of the biology and behavior of numerous species, including Nematobrycon lacortei. This particular species is known for its striking coloration and has become a popular choice among hobbyists and enthusiasts alike.
Classification
Nematobrycon lacortei belongs to the order Characiformes, which is a diverse group of freshwater fish found in South and Central America, Africa, and Asia. The Characiformes order is characterized by the presence of a small adipose fin, lack of an adipose fin spine, and a terminal mouth with teeth on both jaws.
Within the order Characiformes, Nematobrycon lacortei belongs to the family Characidae, commonly known as characins. The family Characidae is one of the largest and most diverse groups of freshwater fish, consisting of over 1,700 species distributed throughout the Neotropics, Africa, and Asia. Characids are known for their laterally compressed bodies, deeply forked tails, and the presence of a well-developed adipose fin.
The genus Nematobrycon, to which Nematobrycon lacortei belongs, is a relatively small group within the family Characidae, consisting of only three recognized species. Members of this genus are characterized by their elongated thread-like rays in the caudal fin, which give them a distinctive appearance.
In summary, Nematobrycon lacortei belongs to the order Characiformes, family Characidae, and genus Nematobrycon.
Distribution
Nematobrycon lacortei is considered endemic to the Río San Juan river system in western Colombia, which drains the departments of Choco and Valle de Cauca. Specifically, all known records of N. lacortei appear to correspond to the Río Calima, a tributary in the lower part of the basin.
The type locality of Nematobrycon lacortei is thought to be the Río Calima in Colombia, but the exact location is uncertain. This species is not known to occur outside of its endemic range and has a limited distribution within its native habitat. The Río San Juan river system is located in the western region of Colombia and is characterized by its fast-flowing, clear waters and rocky substrate.
Due to its restricted distribution and habitat preferences, Nematobrycon lacortei may be vulnerable to threats such as habitat loss and degradation, pollution, and overfishing. Conservation efforts are necessary to ensure the long-term survival of this species and the protection of its unique aquatic ecosystem.
Habitat
Nematobrycon lacortei is known to inhabit small, isolated forest pools in the headwaters of the Río Calima, which is a tributary of the Río San Juan river system in western Colombia. These forest pools are located in the upper reaches of the river, presumably above the Calima Dam, and are characterized by clear water, rocky substrate, and low water flow.
The habitat of Nematobrycon lacortei is quite specific and restricted, consisting of small pools located in forested areas. This species is adapted to these small and often isolated pools and is likely unable to survive in larger or more open bodies of water. The forested habitat surrounding the pools provides important shelter and food sources for this species.
As a result of its limited distribution and specialized habitat requirements, Nematobrycon lacortei may be particularly vulnerable to threats such as habitat loss and degradation, pollution, and changes in water flow. Conservation efforts aimed at protecting and restoring the forested areas surrounding the pools, as well as maintaining water quality and flow, are essential for the long-term survival of this species.
Maximum Standard Length
The maximum standard length recorded for Nematobrycon lacortei is 36.0 mm, based on the largest officially-recorded specimen. Standard length is a measurement of a fish from the tip of the snout to the base of the caudal fin, excluding the length of the filamentous rays.
Nematobrycon lacortei is a relatively small fish species, with most individuals reaching a maximum standard length of around 30 mm. This species is part of a group of fish known as “nano fish,” which are typically less than 40 mm in length when fully grown.
Despite its small size, Nematobrycon lacortei is highly valued by aquarium hobbyists due to its vibrant colors and unique appearance. However, it is important for hobbyists to ensure that they obtain this species from reputable sources and do not contribute to overfishing or illegal collection practices. Conservation efforts are necessary to protect the wild populations of N. lacortei and maintain their unique genetic diversity.
Aquarium Size
Nematobrycon lacortei is a small fish species that is commonly kept in home aquariums. However, due to its active swimming behavior and social nature, it is recommended that they are kept in a spacious aquarium that provides ample room to swim and interact with other fish.
An aquarium with dimensions of 120cm x 30cm x 30cm (or equivalent) should be considered the minimum size for a small group of Nematobrycon lacortei. This size of the aquarium would provide adequate swimming space and allow for the addition of appropriate décor and hiding places.
It is important to note that the water parameters and quality should also be carefully monitored to ensure the health and wellbeing of the fish. Nematobrycon lacortei prefers clear, well-oxygenated water with a neutral to slightly acidic pH. The aquarium should be equipped with a filtration system and regular water changes should be performed to maintain water quality.
Overall, providing a suitable and spacious aquarium is essential for the health and happiness of Nematobrycon lacortei in captivity.
Maintenance
When maintaining Nematobrycon lacortei in an aquarium, it is important to provide a suitable and comfortable environment that meets their needs. The choice of décor is not especially critical, but this species tends to show better coloration when maintained in a well-furnished aquarium with live plants.
A natural-looking arrangement in the aquarium might consist of a soft, sandy substrate with wood roots and branches placed in such a way that plenty of shady spots are formed. The addition of live plants, such as Java moss or Anubias, can also help provide cover and enhance the natural feel of the aquarium.
In addition to live plants and wood, adding dried leaf litter to the aquarium can further emphasize the natural feel and promote the growth of beneficial microbe colonies as decomposition occurs. These beneficial microbe colonies can provide a valuable secondary food source for fry, while the tannins and other chemicals released by the decaying leaves are considered beneficial for the overall health of the aquarium ecosystem.
Water quality is also important when maintaining Nematobrycon lacortei in an aquarium. It is recommended to keep the water well-oxygenated, clear, and with a neutral to slightly acidic pH. Regular water changes and a suitable filtration system should also be employed to maintain water quality.
Overall, providing a natural-looking and well-furnished aquarium with appropriate décor, live plants, and suitable water parameters is key to maintaining healthy and happy Nematobrycon lacortei in captivity.
Water Conditions
Nematobrycon lacortei is a freshwater fish species that requires specific water conditions to thrive in captivity. The following are the recommended water conditions for this species:
- Temperature: 20-28°C (68-82°F)
- pH: 5.0-7.2
- Hardness: 18-179 ppm
It is important to maintain a stable water temperature within this range, as sudden fluctuations can cause stress and health issues for Nematobrycon lacortei. It is also recommended to monitor the pH level and hardness of the water regularly, and make necessary adjustments to maintain optimal conditions for the fish.
In addition to the above parameters, it is important to provide good water quality and adequate filtration. Regular water changes should be performed to keep the water clean and healthy for the fish. It is also recommended to avoid overfeeding the fish, as excess food can contribute to poor water quality and health issues.
Overall, providing the appropriate water conditions and maintaining good water quality is essential for the health and wellbeing of Nematobrycon lacortei in captivity.
Diet
Nematobrycon lacortei is likely an opportunistic omnivore in its natural habitat, feeding on a variety of small invertebrates and plant material. In the aquarium, this species is generally easy to feed, but a varied and balanced diet is recommended to maintain their health and promote optimal coloration.
A diet for Nematobrycon lacortei should include a combination of small live and frozen foods, such as chironomid larvae (bloodworm), Daphnia, Artemia, and other small aquatic invertebrates. These can be supplemented with good quality dried flakes and granules that are specifically formulated for small fish.
It is important to avoid overfeeding this species, as excess food can lead to poor water quality and health issues. It is recommended to feed Nematobrycon lacortei small portions of food several times a day, rather than one large meal. This will ensure that they receive the necessary nutrients and energy to maintain their health and vitality.
Overall, providing a varied and balanced diet that includes live and frozen foods, as well as dried flakes and granules, is essential for the health and wellbeing of Nematobrycon lacortei in captivity.
Behaviour and Compatibility
Nematobrycon lacortei is a relatively peaceful fish species, making it an excellent choice for a well-researched community aquarium. However, it is worth noting that adult males can be territorial and aggressive to some extent, particularly towards similarly-shaped species. Therefore, it is recommended to keep Nematobrycon lacortei with similarly-sized characids, gasteropelecids, lebiasinids, smaller callichthyid or loricariid catfishes, and non-predatory, medium-sized cichlids.
To maintain the natural schooling behavior of Nematobrycon lacortei and reduce stress, it is advisable to purchase a group of at least 8-10 specimens, consisting of both males and females. By including other schooling fish in the aquarium, you can create a more natural-looking spectacle and provide a sense of security for the fish. When kept in a group, the interaction between rival males can be fascinating to watch, particularly when they are competing for female attention or hierarchical position. The males will display their best colors during these interactions, providing an entertaining and visually striking display for the aquarium hobbyist.
Overall, Nematobrycon lacortei is an excellent addition to a well-planned community aquarium, provided that they are kept with appropriate tank mates and in groups of sufficient size. By following these guidelines, you can create an engaging and vibrant aquatic environment that highlights the natural behavior and beauty of these unique fish.
Sexual Dimorphism
Sexual dimorphism is present in Nematobrycon lacortei, with adult males and females exhibiting distinct physical differences.
Adult males of this species possess red eyes and more extended dorsal, anal, and caudal fins compared to females. They are also generally more colorful, with brighter and more vibrant hues than their female counterparts. The red coloration around the eyes is particularly noticeable, and adds to the overall striking appearance of the male fish.
On the other hand, adult females of Nematobrycon lacortei possess blue-green eyes and typically appear fuller-bodied than males, especially when gravid. Female fish may also have a slightly different shape to their dorsal, anal, and caudal fins compared to males, which can help to differentiate the sexes.
Observing these differences can be useful for aquarium hobbyists who wish to breed Nematobrycon lacortei, as it allows for easy identification of males and females. It is important to note that breeding this species in captivity requires specific conditions and careful monitoring to ensure the health and success of the breeding process.
In summary, adult males of Nematobrycon lacortei have red eyes and more extended fins, while females have blue-green eyes and a fuller body. These physical differences provide an easy way to differentiate between the sexes and can be useful for breeding purposes.
Reproduction
Breeding Nematobrycon lacortei is said to be similar to that of its congener, N. palmeri. To successfully breed this species, a small and dimly-lit aquarium should be used, with clumps of fine-leaved plants or spawning mops. Alternatively, a mesh of a large enough grade can be used to cover the aquarium base, allowing eggs to fall through while keeping the adults away from them. It is important to maintain soft and acidic water conditions, with a pH range of 5.0-7.0, gH 1-8, and a temperature of around 75-80°F. A small air-powered sponge filter can also be included in the breeding setup.
To prepare for breeding, it is recommended to condition male and female fish separately. Once the females are noticeably gravid, a single pair should be selected and transferred to the small breeding aquarium in the evening. Spawning typically occurs the following morning, and eggs are deposited in small batches, with spawning continuing for several hours. If eggs are not visible after a couple of days, the fish should be removed and the process repeated with a different pair.
Adult fish will eat their eggs given the chance, so they should be removed from the breeding aquarium post-spawning. Eggs usually hatch in 24-36 hours, with the fry becoming free-swimming 4-5 days later. During the first week or so, the fry should be fed on infusoria-grade food until they are large enough to accept microworms, Artemia nauplii, and other similar-sized food items.
Breeding Nematobrycon lacortei can be an exciting and rewarding experience for aquarium hobbyists. It is important to maintain suitable breeding conditions and closely monitor the breeding process to ensure the health and success of the fry. With the right care and attention, breeding Nematobrycon lacortei can result in a thriving and vibrant community of these unique and fascinating fish.
Notes
The Nematobrycon genus is comprised of two species, both of which are native to western Colombia. The more widespread of the two species is Nematobrycon palmeri, while the other species is Nematobrycon lacortei. While these two species are quite similar in appearance, there are a few morphological differences between them that can be used to differentiate them.
One key difference between N. lacortei and N. palmeri is their modal pectoral-fin ray counts, with N. lacortei having nine rays while N. palmeri has ten. Additionally, N. lacortei has two premaxillary teeth in the outer row, while N. palmeri has three. The mean number of anal-fin rays also differs slightly between the two species, with N. lacortei having 25.8 rays and N. palmeri having 28.1. Finally, the length of the dorsal fin also differs, with N. lacortei having a dorsal fin length of 29.1-30% of their standard length, while N. palmeri has a dorsal fin length of 31.3-49.0% of their standard length.
Despite these differences, the two species possess highly distinctive and easily recognizable color patterns. Nematobrycon lacortei typically has a black body with a white stripe along the midline, while Nematobrycon palmeri has a silver or light-colored body with black markings on the dorsal and anal fins. These color patterns make it easy to identify and distinguish between the two species.
In summary, while Nematobrycon lacortei and Nematobrycon palmeri are quite similar in appearance, there are some morphological differences between them. However, their highly distinctive color patterns make it easy to tell them apart.
References
Weitzman, S. H. and W. L. Fink, 1971 – Beaufortia 19(248): 57-77
A new species of characid fish of the genus Nematobrycon from the Rio Calima of Colombia.
