GloFish® Cory Care Guide - Aquarium Setup, Diet & Breeding

GloFish® Corys are the fluorescent form of the familiar bronze cory, a small armoured catfish with a rounded body, short barbels and rows of bony plates along its sides. Their bright fluorescent colouring makes them especially noticeable under suitable aquarium lighting, while their underlying body shape and behaviour remain characteristic of Corydoras aeneus.

These peaceful bottom-dwellers are active, sociable fish that spend much of their time exploring the substrate with their barbels. They periodically dash to the surface to gulp air, an ability that is normal for Corydoras and helps them cope with oxygen-poor conditions in the wild.

In nature, bronze corydoras inhabit slow-moving streams, flooded forest margins and shallow river environments. They are usually found over sand, fine gravel, leaf litter and soft sediment, where they search for small food items among the debris.

GloFish® Corys are not a separate wild species but a selectively maintained aquarium variety created through genetic modification. Their fluorescence is most striking under blue or actinic-style illumination, and the intensity can vary between individual fish.

GloFish® Corys are a genetically modified fluorescent variety based on the bronze cory, Corydoras aeneus. The original species is native to tropical freshwater habitats in northern and central South America, including parts of Brazil, Colombia, Peru and surrounding regions.

A group of GloFish® Corys should have at least 75 litres, with a footprint of approximately 60 × 30 cm or larger; a longer, wider aquarium is preferable to a tall narrow one. Use fine sand or smooth, rounded gravel that will not damage their sensitive barbels, and provide open bottom space for foraging. Include broad-leaved plants, driftwood, caves and shaded areas for cover, while leaving gentle-flowing swimming space and maintaining good oxygenation.

Adults can reach about 7.5 cm (3 inches) in total length. Females are usually larger and broader-bodied than males, commonly reaching around 6.5–7.5 cm (2.6–3 inches), while males are often about 5.5–6.5 cm (2.2–2.6 inches).

Offer a varied omnivorous diet built around sinking corydoras pellets or wafers, supplemented with frozen or live foods such as bloodworm, brine shrimp, daphnia and mosquito larvae. They also accept softened vegetables and quality small granules. Feed after the aquarium lights have dimmed when possible, and make sure food reaches the substrate rather than assuming they will live on leftovers.

GloFish® Corys are peaceful community catfish and can be kept with similarly calm fish such as small tetras, rasboras, danios, peaceful livebearers, honey gouramis and other non-aggressive Corydoras. They should not be housed with large, predatory or boisterous species, fin-nippers, or aggressive cichlids. Avoid combining them with fish that may outcompete them for food or disturb them continually at the bottom.

GloFish® Corys breed in much the same way as bronze corydoras. Condition a group with varied, protein-rich foods, then encourage spawning with a partial water change using slightly cooler, clean water. The female carries a few adhesive eggs between her pelvic fins before placing them on glass, plants or other smooth surfaces, while the male fertilises them. Adults may eat the eggs, so eggs can be protected or transferred to a separate rearing setup. The fluorescent trait is a result of genetic modification and its inheritance should not be assumed; breeding and sale may also be regulated differently in different regions.

Females are generally longer, deeper-bodied and noticeably fuller through the abdomen, particularly when carrying eggs. Males are smaller and slimmer, with a more tapered profile and often relatively larger, more pointed dorsal and pectoral fins.