7 Different Types of Pencilfish Rare & Common (With Photos)

Pencilfish are a genus of fish belonging to the Characin family Lebiasinidae. There are currently around 20 species of Pencilfish. All members in this genus are known as Pencilfish or Pencil fish, a common name given to two species in the 1920s, Nannostomus eques and Nannostomus unifasciatus. However, by the late 1950s, the name was given to all members of the genus. Several species have become very popular in the aquarium hobby due to their unique shape, Interesting behaviour and attractive colouration.

The majority of the species are slender and pencil-shaped, ranging in size from 2.5 cm up to about 5 cm long. N. rubrocaudatus, N. mortenthaleri and N. marginatus display shortened, blockier outlines that are implicative of pencil stubs. All but a single species, Nannostomus espei, have one to five horizontal brown or black stripes with silver or gold opalescence appearing dorsal to the primary line. Many can display orange, red, or maroon colouration in their fins, and some have bursts of these colours on their flanks.

The newly described N. rubrocaudatus and N. mortenthaleri are particularly vividly coloured. For N espei, horizontal stripes are only sightly present and are replaced by five dark comma-shaped spots. Other species display this pattern at night, but only N. espei shows the pattern permanently.

You will find the adipose fin present in some species but absent in others, while in the case of N. eques, for example, it may be present or absent within the species. All these fish swim in a horizontal position except for N. unifasciatus and N. eques, which have an oblique, up snout posture.

A series of sexual dimorphism occurs in the genus, with males being more coloured in some species, especially concerning colour shown in the fins and far less visible in other species. However, a reliable sign of gender for most of the species is in the anal fin of adult males, which is elongated and enlarged, or the anal fin of males is more vivid. The common aquarium species, N. trifasciatus, is an anomaly in this respect.

Natural habitat

This genus has a vast population in South America, from the southern Amazon Basin and Bolivia to Belem and Brazil in the east to Peru in the west to Venezuela, Guyanas and Columbia in the North. As a result, many species are polymorphic and display ]colour variations depending on where they came from and the population. Over the years, a lot of these colour variants have been mistakenly described as separate species.

Such names as 'Nannostomus ocellatus', 'N. anomalus' and 'N. auratus', amongst many others, are now known to be junior equivalents to the various species. Only two species, N. harrisoni and N. beckfordi, have been commercially raised regularly in Asia. The remaining species that found their way to hobbyists home aquariums are wild-caught from the South American waters. Pencilfish usually inhabit small rivers, swampy areas and sluggish tributaries, especially in places with dense vegetation or submerged leaf litter and woody structures.

Behaviour

Pencilfish are very peaceful, and they can also be quite shy and timid, so bear that in mind when deciding on what sort of fish you will keep them with and avoid boisterous species. A strict hierarchy is established in the group. The individual with the highest rank in the group often takes an upright position.

You can keep Pencilfish as individuals or in groups with their kind where they will feel comfortable. If keeping them in groups, it is advisable to have six or more. It is recommended to house more females than males in an aquarium, which will help prevent aggression between males.

If the females continue to be harassed by the males, it will cause unnecessary stress, so it would be more beneficial to have more females than males. Interestingly, this fish is not aggressive with different species, so it is considered a good tank mate for the community aquarium. However, it is not advised to house these fish with larger, more aggressive fish as they will be outcompeted for food and may die of starvation. When choosing the best tankmates for pencilfish, it is advised to pick other species of Nannostomus and small peaceful Charachins, Corydoras and livebearers such as endlers and guppies.

In the aquarium

Nannostomus species thrive in the home aquarium when provided with soft, moderately acidic water, low nitrate levels, and temperatures ranging between 71 to 82 degrees Fahrenheit. The addition of floating aquatic plants are highly recommended. The following reduces the likelihood of the fish jumping out of the tank, a common occurrence for some species, especially N. unifasciatus and N. espei. Once these fish have been acclimated to the aquarium, they are considered hardy additions, often living for five or more years.

Feeding

When choosing the right food for pencilfish, it is necessary to consider their mouth opening's small size. It is better if you do not feed them with live and frozen food, which cannot fully satisfy the fish's nutritional needs, and in the worst case, can cause disease. A very occasional treat of live or frozen food would be fine.

A more suitable and convenient option is to feed the pencilfish with high-quality dry food; flakes are easily crushed by hand, and they can float for an extended period on the surface of the water, which will allow nannostomuses to get enough. High-quality dried food is also balanced in essential nutrients, contains vitamins and functional additives that affect the digestive system, immunity, and colour.

Breeding

Pencilfish reach sexual maturity around the age of 8 to 10 months. To breed pencilfish at home, you will need a breeding tank with a volume of 5 to 10 litres and a mesh on the bottom with small-leaved plants, such as Javan moss. It would be better to provide low aeration and dim lighting.

You can breed your Pencil fish in either pairs or groups. Whichever method you choose, you must make sure you condition your fish with plenty of food.

To encourage spawning, it is best if you soften the water and raise the temperature. These fish usually spawn at night time. The female lays several hundred eggs on plants' leaves; in some species, the female prefers floating plants' roots.

After the parents have laid their eggs, It is advisable to remove them from the breeding tank and then darken it as the eggs are sensitive to the light. After two to three days, larvae will hatch, and you should feed them on infusoria initially. After about a week you can introduce them to microworm, artemia nauplii and such as they will be large enough to accept them.

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