Eretmodus cyanostictus Breeding Guide

Breeding Eretmodus cyanostictus, a biparental mouthbrooding goby cichlid: pairing, the female-to-male egg transfer, brooding and slow-growing fry.

Overview

Eretmodus cyanostictus is a goby cichlid from the Tanzanian and Zambian shorelines of Lake Tanganyika (Wikipedia). It is a bi-parental mouthbrooder - an unusual strategy among Rift Lake cichlids, which are typically non-pairing maternal mouthbrooders. The pair shares incubation, with the female brooding first and then transferring the brood to the male (Seriously Fish). Genetic and field studies confirm the species is both socially and genetically monogamous (peer-reviewed review of eretmodine parental care).

Sexing

External sexing is unreliable. Spawning males display egg-shaped spots on the anal fin that play a role during fertilisation (Seriously Fish). As with related goby cichlids, the surest approach is to raise a group and let a pair bond form naturally, since pre-selected adults often fight.

Conditioning

This is a grazing species, so condition breeders on a vegetable-based diet supplemented with small invertebrate foods. Strong oxygenation is essential, reflecting the species' fast-flowing, surge-zone habitat (Seriously Fish).

Breeding Setup

Provide a rocky, well-oxygenated tank with strong current. A formed pair remains together for life and defends a territory (Seriously Fish). Breeding is reported at a pH of 8.2-9.0 and a temperature of 77-80 deg F (25-27 deg C).

Spawning Behavior & Trigger

The female selects and cleans a rock surface, then lays 1-2 eggs at a time which the male fertilises before she picks them up; this is repeated until she has laid 10-30 eggs in total (Seriously Fish). The female mouthbroods for over two weeks, not feeding, before transferring the hatched fry to the male, who incubates them a further 7-14 days before release (Seriously Fish).

Egg & Fry Care

After the male releases the fry, the pair may continue biparental guarding (peer-reviewed review). Newly released fry accept brine shrimp nauplii and powdered spirulina-based flake from the first day, but growth is notably slow compared with other Tanganyikan cichlids (Seriously Fish).

Common Challenges

Seriously Fish rates breeding as difficult. Maintaining high oxygenation and strong flow, forming a stable pair, and the small brood size combined with slow fry growth all make this a project for experienced keepers.