Hyphessobrycon simulans Géry, 1963
The genus name Paracheirodon is a combination of two words from different languages. “Para” is a prefix in Ancient Greek that often means “related to” or “beside”, while “cheirodon” is a Greek word that means “hand-toothed” or “hand-toothed fish”. The name “cheirodon” refers to the characteristic teeth of the genus, which are arranged in a way that resembles a comb or saw.
So, Paracheirodon can be understood to mean “related to the hand-toothed fish”, which is a reference to the genus Cheirodon.
The species name simulans is derived from the Latin word “simulans”, which means “imitating, copying”. This name may have been chosen because Paracheirodon simulans closely resembles other species of fish in the genus, such as the neon tetra (Paracheirodon innesi).
Overall, the etymology of Paracheirodon simulans reflects the scientific tradition of using Latin and Ancient Greek to name organisms and describe their characteristics.
Paracheirodon simulans belongs to the Order Characiformes, which is a diverse group of freshwater fish that includes tetras, piranhas, and their relatives. Within this order, Paracheirodon simulans belongs to the Family Characidae, which is one of the largest families of freshwater fish and includes many popular aquarium species.
Characidae are known for their laterally compressed bodies, which are often covered in shiny scales, and their toothed jaws. Many species in this family are brightly colored and highly valued in the aquarium trade for their beauty and ease of care.
Paracheirodon simulans is a small, schooling fish that is native to South America. It is closely related to the neon tetra (Paracheirodon innesi) and the cardinal tetra (Paracheirodon axelrodi), which are also popular aquarium fish.
Paracheirodon simulans is a freshwater fish species that can be found in the middle-to-upper rio Negro drainage in Brazil, upstream of the mouth of its principal tributary, the rio Branco. It is also known to inhabit the Río Orinoco system in the border region of Venezuela and Colombia, specifically between San Fernando de Atabapo and the mouth of the Río Meta.
The original type locality of Paracheirodon simulans was recorded as “Rio Purus, Manaus, Brazil”. However, this was later corrected to the rio Jufaris, which is an affluent of the rio Negro located just upstream of the latter’s confluence with the rio Branco in the Amazonas state of Brazil.
This species is part of the Characidae family, which is known for their toothed jaws, laterally compressed bodies, and shiny scales. Paracheirodon simulans is a small, schooling fish that is closely related to the neon tetra and the cardinal tetra. Like many other Characidae species, Paracheirodon simulans is highly valued in the aquarium trade for its striking appearance and ease of care. Its natural habitat consists of clear, slow-moving waters with abundant vegetation, such as shallow streams, pools, and flooded areas.
Paracheirodon simulans is a unique species compared to its closely related congeners, P. innesi and P. axelrodi. It is an exclusive inhabitant of blackwater environments, typically found only in the upper reaches of tributary drainages in the Amazon basin. Unlike its congeners, it is not found in clear or white water habitats.
The habitats that Paracheirodon simulans inhabits typically contain slow to moderately-flowing water, with thick and often overhanging riparian vegetation, sandy substrates covered in fallen branches, tree roots, and leaf litter. These types of environments provide a natural refuge for the species, which tends to be shy and reclusive.
The water in these habitats is typically acidic, with negligible carbonate hardness and conductivity, and is stained brownish due to the presence of humic substances released by decomposing organic matter. Paracheirodon simulans has evolved to thrive in such environments and has adapted to the low-nutrient and low-light conditions found in blackwater habitats.
Paracheirodon simulans occurs over a similar range to P. axelrodi, but the two species are not found together. Paracheirodon simulans tends to occur in warmer waters and is more commonly found in areas with higher temperatures. The distinct habitat preferences of Paracheirodon simulans make it a unique and interesting species to study for ecologists and aquarium enthusiasts alike.
Maximum Standard Length
The maximum standard length of Paracheirodon simulans is reported to be around 15 to 25 millimeters (0.6 to 1 inch). This is a relatively small size compared to many other species of freshwater fish.
Paracheirodon simulans has a slender, elongated body shape that is typical of many species in the Characidae family. Its small size and attractive coloration make it a popular choice for aquarium hobbyists.
In the wild, Paracheirodon simulans is found in blackwater environments in the upper reaches of tributary drainages in the Amazon basin. It is known to inhabit slow to moderately-flowing waters with thick riparian vegetation and sandy substrates covered in fallen branches, tree roots, and leaf litter.
Despite its small size, Paracheirodon simulans plays an important ecological role in its native habitat as a primary consumer of small invertebrates and other microorganisms. It is also a key food source for larger fish and other aquatic predators.
Understanding the maximum standard length of Paracheirodon simulans is important for both aquarium enthusiasts and researchers studying this species in the wild. In captivity, it is important to provide a suitable environment and diet to ensure the health and well-being of the fish. In the wild, knowledge of its size and distribution can help inform conservation efforts and management strategies for maintaining healthy ecosystems.
When it comes to keeping Paracheirodon simulans in an aquarium, it is important to consider the size of the tank. An aquarium with a base dimension of at least 45 cm by 30 cm (18 inches by 12 inches) is recommended for a small school of these fish.
Although Paracheirodon simulans is a small species, they are active swimmers and require sufficient swimming space to maintain their health and well-being. Keeping them in an aquarium that is too small can lead to stress, disease, and other health issues. In addition to the base dimensions, it is also important to consider the height of the aquarium, as well as the total volume of water it can hold.
A larger aquarium not only provides more swimming space for the fish, but it also provides more stability in terms of water parameters and overall water quality. A larger volume of water can help dilute toxins and other harmful substances, and also provides more stable temperature and pH levels.
It’s worth noting that the recommended aquarium size may vary depending on the number of fish being kept and the other inhabitants of the tank. In general, it is important to research the specific requirements of all fish and aquatic plants being kept together and to ensure that the aquarium is properly maintained and cleaned to maintain a healthy and balanced ecosystem.
Paracheirodon simulans is a relatively easy fish to maintain in an aquarium, although some care is necessary due to the fact that these fish are exclusively collected in the wild. They can be sensitive, especially post-import, so it’s important to ensure that their new environment is stable and well-maintained.
Paracheirodon simulans looks best in a heavily planted set-up or natural-style arrangement, with a sandy substrate, driftwood roots, and branches. The addition of dried leaf litter further emphasizes the natural feel of the tank and provides additional cover for the fish. As the leaves decompose, microbe colonies grow, providing a valuable secondary food source for fry. Additionally, the humic substances released by the decaying leaves are also considered beneficial for the fish, with alder cones also useful in this respect. It’s worth noting that it’s unnecessary to use natural peat, which is both unsustainable and environmentally destructive.
Paracheirodon simulans seems to thrive under fairly dim lighting, and aquatic plant species such as Microsorum, Taxiphyllum, or Cryptocoryne spp. can be added to the tank, as they can survive under such conditions. Floating vegetation, such as Ceratopteris spp., is also appreciated by the fish.
It’s important to note that Paracheirodon simulans is sensitive to fluctuating or deteriorating water conditions and should never be added to biologically immature aquaria. Proper filtration and regular water changes are necessary to maintain healthy water parameters and ensure the long-term health and well-being of the fish.
Paracheirodon simulans is a freshwater fish species that has specific water parameter requirements in order to thrive. In the wild, these fish are typically found in blackwater environments that have unique water chemistry and conditions.
The temperature range for Paracheirodon simulans is between 21 and 35 °C (70 and 95 °F). In its natural habitats, water temperatures have been recorded to range between 24.6 and 35.2 °C (76.3 and 95.3 °F). These fish may have evolved a natural tolerance to high temperatures due to their native habitat. However, it’s important to note that sudden fluctuations or extremes in temperature can be harmful to the fish.
The pH range for Paracheirodon simulans is between 3.0 and 6.5. This is a relatively low pH range compared to many other freshwater fish species. In blackwater environments, the water is typically acidic due to the presence of tannins and other organic acids released by decomposing plant matter. It’s important to maintain a stable pH within this range to ensure the health and well-being of the fish.
The hardness range for Paracheirodon simulans is between 18 and 143 ppm. This is a relatively low to moderate hardness range, and these fish prefer soft water conditions. In their native habitats, the water is typically very low in mineral content, with negligible carbonate hardness and conductivity.
It’s important to note that water conditions can vary depending on the specific location and habitat of the fish. When keeping Paracheirodon simulans in an aquarium, it’s important to replicate their natural environment as closely as possible in order to ensure their health and well-being. This includes providing appropriate water chemistry and temperature, as well as plenty of hiding places and suitable tank mates.
Paracheirodon simulans is likely to be an omnivorous species in the wild, feeding on a variety of small invertebrates, crustaceans, filamentous algae, and fallen fruit. Their diet may also include other organic matter found in their natural habitat.
In an aquarium setting, Paracheirodon simulans can survive on a diet of dried foods. However, as with most fish species, a varied diet is recommended for optimal health and well-being. It is important to offer live and frozen foods in addition to dried foods to meet the nutritional needs of the fish.
Chironomid larvae (bloodworms), mosquito larvae, Daphnia, and Moina are all suitable live and frozen food options for Paracheirodon simulans. These foods provide essential nutrients and are similar to the types of foods the fish would consume in the wild. Offering a varied diet that includes a mix of live, frozen, and dried foods will help ensure the fish receive a balanced diet and maintain good health.
It’s important to note that overfeeding can lead to health problems and poor water quality. Care should be taken to provide appropriate portion sizes and to remove any uneaten food from the aquarium to prevent fouling of the water.
Behaviour and Compatibility
Paracheirodon simulans is a peaceful species that can coexist with other fish in a community aquarium. However, due to their small size and somewhat specialized requirements, they may not be the best choice for a typical community tank.
Ideally, Paracheirodon simulans should be maintained either alone or with other diminutive, non-aggressive characids and smaller callichthyid or loricariid catfishes. In a mixed species aquarium, it’s important to ensure that tank mates are not aggressive or too large, as they may intimidate or even prey upon the smaller Paracheirodon simulans.
Paracheirodon simulans is a gregarious species and naturally forms schools in the wild. Therefore, it’s recommended to keep a minimum of 8 to 10 specimens together in an aquarium. By doing so, the fish will be less shy and display more interesting behavior, including schooling and other natural behaviors.
It’s important to note that keeping Paracheirodon simulans with larger or more aggressive species can lead to stress, injury, or even death. Proper research and careful consideration of the tank’s inhabitants should be taken before adding Paracheirodon simulans to an aquarium to ensure the long-term health and well-being of all fish species involved.
Paracheirodon simulans exhibits some degree of sexual dimorphism, with females being slightly larger and rounder-bodied than males.
Sexual maturity in Paracheirodon simulans is typically reached at around 6 months of age, and it can be difficult to distinguish between males and females until this point. However, once mature, females will often appear noticeably rounder and fuller-bodied than males. Additionally, females may exhibit a slightly deeper body compared to males.
While the differences between males and females in Paracheirodon simulans are not extreme, they may be noticeable to experienced fish keepers. It’s important to note that proper sexing of these fish is important for breeding purposes and for maintaining a healthy and balanced aquarium ecosystem.
This particular species, known as Paracheirodon simulans, is not commonly bred for commercial purposes. As a result, it is less frequently encountered and usually carries a higher price tag compared to its closely-related counterparts. In the aquarium trade, it is sometimes referred to as the “false neon tetra” or “blue neon tetra”.
In the wild, some individuals of this species display a variable number of golden metallic scales. These specimens are often marketed as P. simulans ‘platinum’ or ‘gold’. Interestingly, this condition is said to be caused by a parasite that stimulates increased deposition of guanine in the scales, despite occurring naturally.
To distinguish P. simulans from its congeners P. innesi and P. axelrodi, certain characteristics have been identified. These include the presence of two distinct rows of teeth in the premaxilla, with the outer row containing one or two conical teeth, and the inner row consisting of 4-5 multicuspid teeth with 5-9 cusps. The maxilla is usually toothless but may sometimes have one conical tooth. The dorsal-fin rays typically range from 7-8, with 8 being the norm, while the pectoral-fin rays usually number 7-9, with 8 being the most common. Additionally, P. simulans possess 5-6 branched pelvic-fin rays and exhibit a blue-green lateral stripe on their body that terminates at the caudal-fin base.
For aquarium hobbyists, it may be more useful to note the subtle differences in color pattern. P. simulans can be distinguished from both P. innesi and P. axelrodi by possessing a greener lateral stripe that covers more of the eye/head and extends to the caudal-fin base. Additionally, P. simulans has a lesser amount of relatively duller red pigmentation on the flanks compared to its counterparts.
The taxonomic history of all three species has been somewhat complicated. Earlier authors tended to include them in separate genera based on dental morphology. However, Weitzman and Fink (1983) provided the first evidence for the monophyly of Paracheirodon, containing all three species, via a number of osteological characters plus their distinctive color pattern.
A fourth Paracheirodon species has apparently been discovered in the rio Purus system, but little information is currently available.
The closer relationships of Paracheirodon within the family Characidae have not yet been fully confirmed. Results obtained in the molecular phylogenetic analysis of Oliveira et al. (2011) recovered P. axelrodi to be most closely related to certain members of the Hyphessobrycon species among those included in the study.
Research suggests that the intense blue lateral stripe in Paracheirodon spp. may have evolved as a predator evasion strategy. The hypothesis of Ikeda and Kohshima (2009), published following direct field study of the fish in blackwater streams near Requena in the Peruvian Amazon, suggests that the bright coloration of the lateral stripe in P. innesi is less conspicuous in blackwater except when viewed from a limited angle of around 30° above the horizon. This could aid in confusing predators via bright mirror images of the stripe being projected onto the underside of the water surface.
Interestingly, most characids displaying a laterally-striped color pattern possess a dark-colored lateral stripe with a lighter stripe dorsally. In Paracheirodon, this pattern is reversed, which may be an adaptation for forming such mirror images.
Lastly, P. simulans is capable of adjusting the intensity of their overall color pattern. They become lighter in bright conditions with pale substrate or background and clear water, and duller with a violet lateral stripe at night. This may also be a response designed to make them less visible to predators.
In summary, P. simulans is a unique and fascinating species that is less common in the aquarium trade due to its limited commercial breeding. It can be identified through its distinctive dental and color patterns, and its intense blue-green lateral stripe may serve as a predator evasion strategy in the wild. As research continues, we may learn even more about the fascinating characteristics of this intriguing fish species.
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