Goldfish, scientifically called Carassius auratus, are small freshwater fish belonging to the carp family.
They’re popular pets in indoor aquariums and sometimes become invasive pests in North America when released into the wild.
Originally from China, goldfish were bred for their color over 1000 years ago. There are many breeds with different sizes, shapes, fin types, and colors.
Some variations include Black Moor, Bubble Eye, Butterfly Tail, Calico, Celestial Eye, Comet, and more.
Goldfish live in rivers, lakes, ponds, and ditches with slow-moving or still water. They prefer cold water and thrive in well-vegetated areas.
Their diet consists of plankton, small aquatic animals (benthic invertebrates), plants and debris.
During spawning season female goldfish lay eggs on underwater plants multiple times. Goldfish eggs develop into free-floating young (pelagic larvae).
In captivity, goldfish can live a long time. They can tolerate some saltwater up to 17 parts per thousand but struggle above 15 ppt for extended periods of time.
Goldfish are often used as experimental subjects; they’re valued as decorative fish for ponds and aquariums but are rarely eaten.
To keep goldfish properly in an aquarium you should have at least 5 together with a tank size not less than 40 inches (around 100 cm).
The largest recorded individual goldfish specimen caught by an angler measured around 16 inches long and weighed about 5 pounds.
Goldfish Interesting Facts
- Goldfish were originally bred in China over 1000 years ago for their color, resulting in various breeds and appearances.
- Goldfish eat plankton, small aquatic animals, plants, and debris. They thrive in well-vegetated areas.
- In captivity, goldfish can live a long time.
- The largest recorded goldfish caught measured around 16 inches long and weighed about 5 pounds.
Goldfish Habitat
Goldfish is native to central Asia, China, and Japan. It has been introduced worldwide and can sometimes negatively impact local ecosystems.
This fish lives in brackish and freshwater environments. It swims near the bottom of water bodies (benthopelagic) and migrates within rivers (potamodromous).
Goldfish prefers a pH level between 6.0 to 8.0, a hardness range of 5 to 19 dH, and depths of up to 20 meters.
The optimum water temperature for goldfish ranges from 68°F to 72°F (20°C to 22°C).
It prefers warmer waters (subtropical), typically found between latitudes of 53°N and 22°N.
| Water Temperature: | 68°F to 72°F (20°C to 22°C) |
| Water pH: | 6.0 to 8.0 pH |
| Water Hardness: | 5 to 19 dH |
Goldfish Physical Characteristics
Size: 10.0 inches (25.4 centimeters)
Goldfish can grow up to 19 inches (around 48 cm) long, but they’re commonly around 4 inches (10 cm) long. They can live for up to 41 years in the wild.
Their bodies are thick and stout, with a short and thick tail area. The head is triangular, without scales, and has a wide space between the eyes.
These fish have no barbels on their upper jaw. They have a complete lateral line and fins with serrated spines.
Male goldfish develop small bumps called nuptial tubercles during mating season. Goldfish can easily breed with carp, producing offspring with mixed traits.
They have 17 to 19 rays in their tail fin and a serrated anal ray.
In the wild, goldfish colors range from olive brown to creamy white, often with bronze or silver tones.
Cultivated varieties come in various colors like red, pink, silver, brown, white, black, or combinations of these colors.
Goldfish Reproduction
Goldfish needs cold water in winter for healthy egg development. They spawn (lay eggs) in shallow water with plants and exposed willow roots or flooded meadows.
Spawning happens from just before dawn until midafternoon. Each fish lays 3 to 10 sets of eggs every 8 to 10 days during the spawning season.
Baby goldfish need warm temperatures to grow well.
The sticky eggs attach to underwater plants and objects. Female goldfish lay eggs multiple times during the spawning period.
Goldfish Scientific Classification
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Cypriniformes |
| Family: | Cyprinidae |
| Genus: | Carassius |
| Scientific Name: | Carassius auratus |
| Also Known As: | Goldfish |
| Conservation Status: | Least Concern |