Photo thanks to japes

Name:
Scientific name: Nannostomus marginatus
Common name: Dwarf Pencilfish
AKA: Nannostomus marginatus picturatus (previously thought to be a seperate sub-species of N. marginatus).

Country of origin: South America - Peru, Brazil, Columbia, Guyana

pH: 4.0 - 7.0
Temperature: 22 - 28c
Hardness: 18 - 179 ppm
Water flow: low - standard
Oxygenation: standard

Maximum size: 2.5cm


Diet: Live, frozen, flake & pellet food of a siutable (very small) size - they are micropredators. They will benefit from daily live food.

Breeding:
Males: slimmer

They are an egg scatterer, and if provided with a mop or sufficient moss or plants, they can lay eggs, however they need to be kept from them by a division in the tank, or removal of the eggs or fish. They will predate on both their own eggs and fry.

Tank companions: They are probably the best pencilfish with shrimps, although they will still hunt shrimplets.

Other microfish are suitable tankmates, such as bororas; danios; chocolate, liquorice & sparkling gouramis; green neon & ember tetras; male endlers and royal whiptails, although they are very shy, so a species only tank is preferable. They live in their natural habitat with apistogramma species. Despite their continual non-stop hunting of shrimplets, I have never observed them to display any aggression toward or interest in other fish as prey.

They should be kept in a group of 10+, which will help to spread aggression, although they rarely hurt each other.

They swim at the middle to top of the tank.

Tank:
Mimimum tank size is 1.5ft for a small group.

They prefer a dark substrate, heavily planted, with blackwater from decaying leaves (Indian Almond Leaves are ideal) and floating plants.

They require a mature tank - do not add them immediately after setting up a new tank.

Their colour will probably fade when the lights are off, and return gradually as the lights come on. They can have a diagonal bar pattern after lights off.


Confused with:
Nannostomus marginatus has some colour variations, depending on locality - from a mustard yellow to buff, the buff varieties can have a short or longer red line above the central black line or blending into it respectively.

There are 19 species in the genus:

Nannostomus anduzei
Nannostomus beckfordi - Gold line/ Beckford's/ Golden/Brown pencilfish
Nannostomus bifasciatus - Two-lined/whiteside pencilfish
Nannostomus britskii - Spotstripe pencilfish
Nannostomus digrammus - Twostripe pencilfish
Nannostomus eques - Honeystick/Brown/Rocket/Brown-tailed/Diptail/Tubemouth pencilfish
Nannostomus espei - Espe's/Barred pencilfish
Nannostomus grandis
Nannostomus harrisoni - Harrison's/blackstripe pencilfish
Nannostomus limatus - Elegant pencilfish
Nannostomus marginatus - Dwarf pencilfish
Nannostomus marilynae - Marilyn's/greenstripe pencilfish
Nannostomus minimus - Least pencilfish
Nannostomus mortenthaleri - Coral-red pencilfish
Nannostomus nigrotaeniatus
Nannostomus nitidus - Shining pencilfish
Nannostomus rubrocaudatus - Purple pencilfish
Nannostomus trifasciatus - Threestripe/Three-lined pencilfish
Nannostomus unifasciatus - Oneline pencilfish

All Nannostomus spp. are legal imports to Australia as of 20/10/2013:
http://www.environment.gov.au/biodiv...mport-list.pdf

The IUCN Red List reports Nannostomus marginatus as a species which has not yet been assessed at 21/10/2013:
http://www.iucnredlist.org/search

It is very important not to release any aquarium specimens into our waterways. Any that are not sold or re-homed/ given away, can often be re-sold to aquarium stores. If they are homed in ponds, care should be taken that they cannot escape in run-off into our waterways. Even if fish are native & local they should not be moved from one waterway to another, as this can transfer disease. If they are not local fish, they can both spread disease and either out-compete or eat local fish, shrimp & plants, causing their demise.

They are a good fish for people with some experience (beginners +1).

Relevant threads:
Video of dwarf pencilfish:
http://www.aquariumlife.com.au/showt...ght=pencilfish

Diet:
http://www.aquariumlife.com.au/showt...ht=nannostomus

Video, keeping/treating with tea-tree & other advice:
http://www.aquariumlife.com.au/showt...ht=nannostomus

Video of males sparring, keeping with shrimp:
http://www.aquariumlife.com.au/showt...ht=nannostomus

Breeding:
http://www.aquariumlife.com.au/showt...ht=nannostomus