Girardinichthys multiradiatus

Girardinichthys multiradiatus, the Crescent Goodeid or Amarillo, is one of the smallest goodeid livebearers, with males reaching only about 4–5 cm. Males display striking sexual dimorphism with enlarged, colourful fins compared to the plainer females. This species is critically endangered due to the destruction of its high-altitude lake habitats in Mexico.

Conservation breeding by hobbyist groups and specialist fish societies plays an essential role in preserving this species. It requires cooler, clean, oxygen-rich water — warmer temperatures stress the fish and shorten lifespans significantly.

This is an ideal fish for the conservation-minded hobbyist willing to maintain the specific conditions required. Groups should be kept in species tanks or with other goodeids of similar size.

Water: 16–22 °C, pH 7.0–8.0, GH 6–15; cool, well-oxygenated water is essential. Tank: 60 L minimum; good surface agitation for oxygenation; cool room temperatures preferred. Feeding: Small live foods (Daphnia, micro-worms), quality flake; 2 small meals daily. Breeding: Goodeid; internal gestation approx. 60 days; 5–20 fry per litter; no parental care. Compatibility: Peaceful; best in species tank or with other small, cool-water goodeids.