Laimosemion xiphidius Breeding Guide

Breeding the sword-tail rivulus Laimosemion xiphidius: a non-seasonal blackwater killifish that lays eggs among plant material and is not prolific.

Overview

Laimosemion xiphidius (described as Rivulus xiphidius) is a small South American killifish of the Oyapock River basin and adjacent coastal drainages. FishBase records it from very shallow parts of small brooks where water is brown and rich in tannin over decaying vegetation, and classifies it as a non-seasonal killifish, so the eggs do not require a dry diapause.

Sexing

FishBase gives males a maximum of about 4.5 cm total length and females 3.0 cm, with sexual differentiation at roughly 3-4 months of age. Males carry the black-and-yellow striped tail and metallic blue body of display fish.

Conditioning

First reproduction occurs around one year of age. Mature adults should be conditioned on small live and frozen invertebrate foods in soft, acidic, tannin-stained water; FishBase lists pH 6.0-6.5 and 22-25 C for the species.

Breeding Setup

A tightly covered nano blackwater tank suits this jumper. Provide fine-leaved plants, moss and leaf litter as spawning sites in dim, soft, acidic water matching its natural brooks.

Spawning Behaviour & Trigger

FishBase notes dominant males are followed by one to three females during spawning and describes the species as not prolific. Eggs, about 1.6 mm in diameter, are deposited among plant material; the fish is a non-annual plant-spawner rather than a soil-diapause species.

Egg & Fry Care

Because output is low, eggs can be left in a quiet, well-planted tank or gently collected for separate incubation in water from the parents' aquarium. Free-swimming fry are small and take microscopic foods before progressing to newly hatched brine shrimp.

Common Challenges

The species is demanding: it needs stable soft acidic water, is prone to jumping, and is not prolific, so a tight lid and patience are essential. Stable parameters and a steady microfauna for fry minimise losses.