Introduction to The Glofish

The GloFish (also known as Danio rerio) is a favoured tropical freshwater aquarium fish. It belongs to the Cyprinidae family of fish, under Order Cypriniformes and Class of Actinopterygii. It is also known as the zebrafish and is indigenous to streams of the southeastern Himalayan region.

It is distributed in parts of Burma, Bangladesh, India, Nepal and Pakistan. This particular species occupies canals, slow-moving or stagnant water, ditches, ponds and streams. The GloFish is a crucial vertebrate model organism in scientific research due to its remarkable regenerative capabilities. At present, it is modified by researchers to produce several transgenic danio.

A school of genetically modfied Glofish


The GloFish has fusiform and a laterally shortened body, with an upward directed mouth. Its eyes are centrally located, and has thin, elongated mandibles with a protruding lower jaw. The body of this Zebrafish consists of a partial lateral line, and two pairs of barbells.

There are five orderly pigmented horizontal blue stripes on the side of the body which, resembles the stripes of a Zebra that extend to the end of the caudal fin.  The Anal fin is distinctively striped, with 10-12 branched fin rays.

It is an omnivore, and in the wild its food primarily consists of algae, vascular plants, insects, spores, invertebrate eggs, a variety of other foods such as worms and crustaceans and also zooplankton. It can also take food from the waters surface as arachnids and terrestrial insects.

In the wild, the GloFish is preyed upon by the common Kingfisher, Indian pond Heron, catfish, snakeheads, freshwater garfish, knifefish and Spiny eels. The zebra fish can grow up to 7.6 cm in length and its life span ranges from 2 to 5 years.


Glofish Care Facts

Scientific Name : Danio rerio

Common Names : Glofish – Starfire Red®, Electric Green®, Sunburst Orange®, Cosmic Blue®, Galactic Purple®, Red Danio, Green Danio, Orange Danio, Blue Danio, Purple Danio

Care Level : Easy, a great choice for freshwater beginners

Lifespan : 2 – 4 years, sometimes up to 5 years

Size : Up to 2 inches (5 cm)

pH : 6.5 – 8

Temperature : 65°F – 75°F (18°C – 24°C)

Water Hardness : 5° to 19° dH,

Origin / Habitat : Glofish are aqua cultured

Glofish Breeding : Glofish breeding is prohibited due to licensing restrictions

Temperament / Behavior : Mostly peaceful when kept in groups of 6 or more with occasional fighting and chasing among the group.

Aquarium Size : 10 gallons or larger for more stable water parameters.

Tank Mates : Glofish can be kept with other barbs, angelfish, danios, tetra and other freshwater fish species not big enough to eat them.

Fish Disease : Freshwater Fish Diseases – in general the Glofish is considered a hardy fish but has been noted to be susceptible to velvet disease, mycobacteriosis and intestinal capillariasis (ref:

Diet / Foods : A good tropical fish flake food rotated with brine shrimp and other fresh foods occasionally.

Gender : Distinguishing male from female when glofish are young can be difficult, however, as adults, females should develop a more pronounced stomach when carrying eggs.


A blue and yellow variation

Housing GLOFISH ®

GloFish are a very rugged fish, and considered a good fish for novice aquarium hobbyists. This fish can adapt to most aquarium conditions. A tank of least 15 gallons or larger is required to keep the fish healthy and happy. They also do well in shoals or schools of six or more. They spend most of their time in the top and middle regions of the tank. This is a placid fish and should be housed with other placid fish such as barbsm angelfish, tetra, other danios and other freshwater fish that are of similar size.

Aquariums are closed systems, and it always needs some sort of maintenance. Phosphate, nitrates and organic matter build up overtime in the aquarium, and the water density can increase due to evaporation. Utmost care should be taken, and 25-50% of the water should be replaced at least once a month. If the tank is heavily stocked, 20-25% water should be replaced weekly or every other week. The aquarium needs an ample filtration system to provide adequate water movement and the tank should be covered with lid as this fish is known to jump.

Feeding GLOFISH ®

The GloFish or zebrafish is an omnivore, and they acquire their food from the water column that primarily eats algae, vascular plants, insects, spores, invertebrate eggs and a variety of of other foods such as worms and small crustaceans, as well as zooplankton. GloFish also takes food from the water’s surface, such as arachnids and terrestrial insects. In the aquarium, they eat any prepared or live aquarium foods. Common tropical flake food should be fed in small batches 2- 3 times per day. They also eat freeze-dried shrimp. A variety of food should be fed for the optimal health of your GloFish. Fry can initially be fed microorganisms or live Paramecium. At around the 9th day, they can be fed brine shrimp.

Breeding GLOFISH ®

Danio rerio is considered very easy to breed in an aquarium. Its group is egg scatterers and group spawners. It is a social and active fish which breeds seasonally during the monsoons that ranges from April to August. It usually breeds in silt-bottomed and well vegetated pools. In captivity, gravel spawning sites are favoured to silt spawning sites. The water temperature (78°F) of the aquarium should be sustained, and feeding the female with high quality foods. The female can lay 100 non-adhesive eggs without preparing a nest in each clutch at 2-3 day intervals.

The Zebrafish spawns every 1 to 6 days during spawning season that occurs once a year.  Breeding is motivated by temperature, and food availability also acts as cue for breeding. Hatching time also depends on water temperature which should optimally be 83.3 °F.  Most eggs hatch between 48 and 72 hours after fertilization. A Hatchling is approximately 3 mm in size, and becomes instantly independent. They are able to feed, swim and exhibit active avoidance behaviours within 36 to 72 hours of fertilization.

A bright orange glofish

Photo Source

Sexing GloFish ®

The male GloFish are indistinguishable from the female during juvenile stage, but at adult stage it is easier to spot differences between the male and female GloFish. The male has torpedo-shaped body with gold stripes in-between the blue stripes, where the female has a larger, whitish belly and silver stripes instead of gold stripes. The male also has a more yellow colour and larger anal fins than the females. Adult females display a small genital papilla in front of the anal fin. During breeding time, the female develops a more defined stomach while carrying eggs.