🐟 Red Pencil Tetra (Nannostomus mortenthaleri)
A Slender Body With Vivid Red Horizontal Stripes Separated by Black and Cream • A Naming Note: A Pencilfish, Not a True Tetra • One of the Most Colourful Nano Fish Relative to Its Size
 
A note on naming: the Red Pencil Tetra, also known as the Coral Red Pencilfish or Red Arc Pencilfish, is actually a pencilfish rather than a true tetra, belonging to the family Lebiasinidae rather than Characidae, despite the common trade name.
 
📋 The Red Pencil Tetra has a slender, elongated body displaying vivid red horizontal stripes separated by bands of black and cream, one of the most colourful nano fish available relative to its size. Males show the most intense colouration, while females are paler but still attractive.
It comes from Peru, specifically the upper Rio Nanay river basin in the Amazon, a soft, acidic blackwater habitat. Every Red Pencil Tetra we ship is feeding well.
This is an active, schooling species that hovers among plant stems and hardscape in the middle to upper water column. Males can be mildly territorial toward each other, displaying intensely with spread fins and deepening red colouration, though the species is peaceful toward other fish. A diet rich in natural colour enhancers helps maintain its brightest red. It reaches up to 4cm, so a 40L tank suits a school well.
 
💡 Highlights
🔴 Vivid Red Striped Body: One of the most colourful nano fish relative to its size
🔍 A Naming Note Worth Knowing: A pencilfish, not a true tetra
🌱 From Blackwater Peru: The upper Rio Nanay river basin in the Amazon
👥 True Schooling Fish: Best kept in groups of 8 or more
🎨 Diet Affects Colour: A varied diet helps maintain its brightest red