Ten-spotted Livebearer (Cnesterodon decemmaculatus) Breeding Guide

Breeding the nano livebearer Cnesterodon decemmaculatus: sexing by gonopodium, a 24-day gestation, small broods of 5-15 young, and protecting the tiny fry.

Overview

Cnesterodon decemmaculatus is a tiny South American livebearer of the family Poeciliidae found in Bolivia, Brazil, Paraguay, Uruguay and Argentina. It inhabits calm, well-vegetated shallow streams and drainage ditches and is unusually tolerant of cooler water, which makes it a hardy nano species. Like other poeciliids it bears live young rather than laying eggs.

Sexing

Males carry an angled, anteriorly placed gonopodium formed from the anal fin and remain slender. Females are plumper and their body bulges progressively as gestation advances. The species is small overall, so a magnifier helps when sorting young breeders.

Conditioning

Condition adults on small live and frozen foods such as daphnia and microworms alongside fine prepared food. The fish accepts a wide temperature band and breeds well in moderately warm water; aquarium temperatures of around 27 °C are reported, and it can endure water heated to about 30 °C in the warmest season while also tolerating cool conditions.

Breeding Setup

A small, densely planted species tank with calm water mimics its natural ditches and streams. Provide thickets of fine-leaved and floating plants so newborns can escape predation. The peaceful temperament means a small group of one or more males with several females will breed continuously without aggression.

Spawning Behavior & Trigger

Fertilisation is internal. After a gestation of about 24 days the female releases five to ten, and rarely up to fifteen, fully formed young measuring roughly 2 to 2.5 mm. The fry are large enough to take microworms, baby brine shrimp and powdered foods at once. Sexual maturity follows after the third or fourth month, allowing rapid colony growth.

Common Challenges

Because broods are small and the fry are minute, the chief challenge is protecting young from being eaten and providing food fine enough for their tiny mouths. Dense planting and frequent small feedings of infusoria-grade food give the best survival.