Black Chin Livebearer Care Guide - Aquarium Tips, Diet & Breeding

The Black Chin Livebearer, Girardinus metallicus, is a small Cuban poeciliid named for the dark marking that develops around the lower jaw and chin. Its body has a silvery, metallic sheen, while mature males often show stronger patterning and a more slender shape than females.

Like other livebearers, this species gives birth to free-swimming young rather than laying eggs. It is an active, alert fish that spends much of its time exploring open water and picking at surfaces for small food particles and algae.

In the wild, Black Chin Livebearers inhabit freshwater environments ranging from calm pools to gently moving streams. Their natural waters can be relatively hard and alkaline, and vegetation commonly provides shelter and feeding areas.

They are generally peaceful community fish, although males may court females persistently. Their interesting reproductive behaviour, metallic colouration and manageable adult size have made them a distinctive choice for keepers interested in less commonly seen livebearers.

The Black Chin Livebearer is native to Cuba in the Caribbean, where it occurs in freshwater streams, pools and other quiet or gently flowing habitats. It is associated with warm, mineral-rich waters across parts of the island.

A group of Black Chin Livebearers should be given an aquarium of at least 60 litres, with a footprint around 60 × 30 cm or larger. Use a secure cover, gentle to moderate filtration and open swimming space alongside dense planting, including fine-leaved or floating plants that provide shelter for fry. A sandy or fine-grained substrate, smooth décor and some wood or rock create a natural-looking layout, while good circulation and clean, well-oxygenated water help maintain stable conditions. Keep the water moderately hard and alkaline, around 20–26°C with a pH of approximately 7.0–8.5.

Females can reach about 7 cm (2.8 inches), while males are usually smaller at around 4 cm (1.6 inches).

Offer a varied omnivorous diet based on quality flake or small pellet food, supplemented with algae-based foods and regular portions of blanched vegetables such as spinach, courgette or shelled peas. Small live or frozen foods, including brine shrimp, daphnia and bloodworm, provide useful variety, particularly for growing fish and females producing fry. Feed small portions that are consumed quickly, and include plant matter because the species naturally grazes on algae and biofilm.

Black Chin Livebearers can share a peaceful aquarium with similarly sized, calm fish such as small tetras, rasboras, danios, peaceful barbs, Corydoras and other gentle livebearers that appreciate hard, alkaline water. Keep them in a group with more females than males to reduce persistent male attention. Avoid aggressive species, large predators and fin-nipping fish, as well as delicate soft-water species whose water requirements conflict with those of this Cuban livebearer.

Black Chin Livebearers are easy to breed when kept as a mixed-sex group. The male fertilises the female using his gonopodium, and pregnancy usually lasts around four to six weeks. A female may produce roughly 20–60 fully formed fry, depending on her size and age. Dense floating plants, moss and other cover give the young fish places to hide, as adults may eat some of the brood. Remove or protect the fry if a high survival rate is desired.

Females are noticeably larger and fuller-bodied than males, especially when carrying developing young. Males are slimmer, have a more pronounced dark chin marking and possess a gonopodium, the modified anal fin used for internal fertilisation.