The Coral Red Pencilfish (Nannostomus mortenthaleri) is one of the most vibrant, sought-after nano fish in the freshwater aquarium hobby. Renowned for its brilliant ruby-red body and jet-black horizontal stripes, this stunning species adds an unmatched pop of color to planted community tanks.

Product Description

Place of Origin Native to South America, the Coral Red Pencilfish originates from slow-moving forest streams, small tributaries, and flooded forest areas within the Peruvian Amazon basin, particularly around the Nanay and Tigre river basins.

Care & Water Parameters While moderately hardy once established, they thrive best in clean, well-filtered, soft, and slightly acidic water.

• Temperature: 75°F – 82°F (24°C – 28°C)

• pH: 5.5 – 7.0

• Hardness: 1 – 8 dGH

• Care Level: Moderate

Minimum Tank Size A minimum tank size of 15 to 20 gallons is recommended. Males can display territorial behavior toward one another, so providing ample swim space and visual barriers helps keep peace in the aquarium.

Environment & Setup To replicate their natural blackwater habitat, keep them in a densely planted aquarium with driftwood, submerged root structures, and leaf litter. Floating plants like Frogbit or Salvinia are highly recommended to dim light levels and promote their rich, natural red coloration. Gentle filter flow is ideal.

Diet & Feeding Coral Red Pencilfish are micro-predators with small mouths. Feed them a varied diet consisting of high-quality micro granules, crushed flakes, and live or frozen foods such as baby brine shrimp, daphnia, and cyclops.

Tank Mates Keep them in groups of 6 or more (ideally with a higher ratio of females to males) to dilute male squabbles and encourage schooling. Excellent tank mates include small peaceful tetras, rasboras, dwarf dwarf cichlids (Apistogramma), Corydoras catfish, and peaceful dwarf shrimp. Avoid large or aggressive tank mates.

Breeding They are egg-scatterers that deposit non-adhesive eggs among dense vegetation like Java Moss. Breeding requires very soft, acidic water (pH 5.5–6.0). Because adults will eat their own eggs and fry, use a separate dedicated breeding tank with a mesh grate or dense spawning moss, removing parents immediately after spawning.

PLEASE READ BEFORE ORDERING

• The photos shown on fish product pages are representations of adult fish and are NOT the actual fish that you will be receiving. 
• Please visit our “Ordering/Shipping fish” page prior to checking out to familiarize yourself with our process.
• We ship fish exclusively using overnight shipping with either FedEx or UPS. We will not ship fish with lesser expensive shipping services like “Ground” or “Priority Mail”. This is to ensure the safety of the fish.
• Unless specified, all fish are sold as unsexed.