Aphanius iberus Breeding Guide

Breeding the Iberian toothcarp Aphanius iberus: a brackish-tolerant, Near Threatened seasonal spawner that lays eggs on plants from spring to early autumn.

Overview

Aphanius iberus, the Iberian or Spanish toothcarp (family Aphaniidae), is endemic to the Mediterranean coast of Spain, where Wikipedia and FishBase report it from lagoons, salt marshes, swamps and estuaries in lowland waters with minimal current. It is euryhaline, tolerating salinity up to about 57 ppt. The IUCN lists it as Near Threatened (2023), and it is threatened by habitat loss and the introduced mosquitofish Gambusia affinis.

Sexing

FishBase gives males to about 5.5 cm and females to 5.4 cm total length. Males show the blue-and-silver display colouration, while females are larger-bodied at equivalent age and more subdued.

Conditioning

An egg-laying carnivore, the species conditions well on small live and frozen invertebrates. Wikipedia notes maturity at about three months. Slightly brackish hard water suits it; FishBase lists pH 6.5-7.5 and a broad temperature tolerance of 10-32 C.

Breeding Setup

A well-planted tank with fine-leaved plants or filamentous algae provides the egg-laying sites. As a brackish-tolerant species, slightly saline hard water mirrors its coastal-lagoon origins and suits both adults and developing eggs.

Spawning Behaviour & Trigger

Spawning is seasonal, running roughly April to September (FishBase), or April-August in southern populations and May-August in the Ebro Delta (Wikipedia). Females spawn repeatedly each season, producing from about 100 to 900 eggs, deposited on aquatic plants or filamentous algae.

Egg & Fry Care

Wikipedia gives hatching at approximately 8 days after laying. Eggs can be left on plants in a low-predation tank or transferred for separate incubation; fry take small live foods once free-swimming.

Common Challenges

As a threatened species, captive maintenance of genetically managed stock is important; predation by adults on eggs and fry, and competition from any introduced Gambusia, are key risks. Seasonal cooling and a brackish, hard-water setup help cue spawning.