About the Golden Pencilfish
Species Type: Freshwater Fish
Care Level: Easy. Does well in a slightly more narrow range of water parameters and shouldn't be used to cycle an aquarium. Will eat most prepared foods. May have some specific care requirements in terms of particular water parameters, social behaviors, food items etc.
Origin: Native in the rivers of Guyana, French Guyana, Suriname; lower and middle Amazon basin and lower Rio Negro, Brazil.
Compatibility/Temperament: Generally peaceful, but males regularly chase other fish away from their area; while this is generally not physical, it can be depending upon the fish--surface fish like hatchetfish will often be harassed and nipped. Males frequently display/challenge each other, sometimes three in a line, but more often two together. Males drive females very hard, and there should be more females than males to ease stress. In a community aquarium, this pencilfish is better with more active fish than any of the other species, and should not be combined with sedate fish like angelfish, discus, gourami.
This is the most active species of pencilfish and is therefore suitable for community aquaria with other lively but peaceful non-aggressive fish such as tetras, corydoras, small loaches, rasbora, danio, and apistogramma. As it spends considerable time at or close to the surface, it is not recommended with surface fish. Must be kept in a group, preferably 8 or more, with a ratio of more females than males, e.g., 5 females to 3 males. Sexual dimorphism is quite easy; males often have broader black bands on their sides and are far more brick red (darker, almost black at times) in comparison to the females who are beige in color and less attractive; the first (left) photo above is a male, the second photo is a female.
Males continually establish conflicts which are entertaining and not likely to result in physical harm; they position themselves parallel to each other with face forming a 45 degrees downward angle. They try to push each other aside by their flanks. Sometimes, about three males perform such dominance and this is even more entertaining than the actual two. Photo 3 illustrates 2 males in "combat."
In the wild, this species inhabits sluggish streams and quiet waters. A well-planted tank with a dark substrate and subdued lighting makes a perfect environment for the pencilfish. Leaf litter on the substrate is appropriate, and floating plants should always be present; the fish graze among the dangling roots and will spawn among floating plants and the upper parts of stem plants. The fish move about the aquarium but tend to remain in the upper 2/3 of the water column.
As with all pencilfish, except for N. espei, they have a diurnal (different from day to night) colour pattern; in darkness the lateral stripe breaks up into blotches and the colours pale considerably. This has been observed in blind fish, showing that it is an automatic response and not controlled by the fish.
This species does not posses an adipose fin. As with all pencilfish, the mouth is small, terminal and always open, adapted for feeding on very small organisms. The genus name Nannostomus comes from the Greek for "small mouth."
Most available fish are now commercially raised. The species was first described and named as Nannostomus beckfordi by Gunther (1872). There are several colour variations or morphs known, and subsequent to the original naming by Gunther, he or other scientists variously assigned the names Nannostomus anomalus, N. aripiragensis, N. surinami and N. simplex to different colour morphs of this fish under the impression they were distinct species. Weitzman (1966) determined that these are conspecifics and the names are now recognized as synonyms (i.e., invalid) for N. beckfordi. This is a polytypic species with a wide geographical range from the Guyanas and along some 700 air miles up the Amazon River in tributary streams and rivers; further study will likely determine that this species consists of several distinct geographical populations and some of these may prove to be subspecies (Weitzman 1966, Weitzman & Cobb 1975).
All pencilfish are found in the tribe Nannostomini in the subfamily Pyrrhulininae. Three different genera (Nannostomus, Nannobrycon and Poecilobrycon) were used at various times until Weitzman & Cobb (1975) placed all species in the single genus, Nannostomus, erected by Gunther in 1872 with the present species as the type; Gery (1977) separated them into two genera, Nannostomus and Nannobrycon, largely on the basis of the swimming position. Weitzman & Weitzman in Reis et al. (2003) reassigned the species into the single genus Nannostomus which now includes all described pencilfish.
Gery, Jacques (1977) "Characoids of the World," TFH Books.
Reis, R.E., S.O. Kullander & C.J. Ferraris Jr. (2003), "Check list of the freshwater fishes of South and Central America."
Weitzman, Stanley H. (1966), "Review of South American Characid Fishes of Subtribe Nannostomina," Proceedings of the United States National Museum (Smithsonian Institution), Volume 119, Number 3538.
Weitzman, Stanley H. & J.S. Cobb (1975), "A revision of the South American fishes of the genus Nannostomus Gunther (family Lebiasinidae)," Smithsonian Contributions to Zoology No. 186.
Golden Pencilfish Diet
Give the small size of their mouths consideration. Will readily accept prepared foods; bloodworms, brine shrimps, tubifex worms and mosquito larva are appreciated.
Can attain 2.5 inches, but usually around 2 inches.
Minimum Tank Suggestion
24 inches in length
Ideal water parameters for Golden Pencilfish
Soft to moderately hard (< 12 dGH), slightly acidic (pH 6.0 to 7.0) but can tolerate slightly basic (pH 7.2-7.5) water, temperature 24-26C/75-79F. Fish will be more colourful in slightly acidic and soft water, and spawning will be frequent.