Species NameCarassius auratus
Common NameGoldfish
Care LevelModerate
LifespanUp to 25 years (with proper care)
Adult Size6-8 inches (15-20 cm) but can grow larger in ponds
Minimum Tank Size20 gallons (75 liters) for a single goldfish
Temperature65°F – 75°F (18°C – 24°C)
Water ConditionspH 7.0-7.5, Medium hardness

About the Goldfish – Species Summary

Few fish can claim the universal recognition that goldfish enjoy. From humble beginnings in East Asia over a thousand years ago, the goldfish, Carassius auratus, has swum into households and public spaces across the world. They were initially kept by Chinese elites, and their domestication dates back to the Tang Dynasty. Today, with their wide variety of colors, shapes, and sizes, they are a staple in the aquarium hobby and are celebrated both for their beauty and their cultural significance.

The myth that goldfish belong in bowls, thriving in limited space with little care, has long been debunked. Goldfish are active, inquisitive creatures that require proper care and a suitable environment to thrive. The stereotypical image of a small, orange fish is just the tip of the iceberg when it comes to the diversity of goldfish varieties available.

Goldfish Lifespan

Goldfish are incredibly long-lived when provided with appropriate care. In an optimal setting, they can live anywhere from 10 to 25 years, with some even reaching 30! However, their longevity is often compromised due to confined spaces, inadequate water quality, and improper diets. Given the right conditions, goldfish not only live long but flourish, displaying vibrant colors and active behaviors.


There is an astounding range when it comes to goldfish appearance. From the traditional orange to shades of yellow, white, black, and even blue, their color palette is vast. Moreover, there are various types of goldfish, each with unique physical attributes. From the flowing double tail of the Fantail and Ryukin to the distinct head growth on the Oranda and the telescope eyes of the Black Moor, the world of goldfish is rich in diversity.

Average Size

A common misconception is that goldfish remain small throughout their life. However, depending on the variety and environment, they can grow from 6-8 inches (15-20 cm) in tanks to even a foot or more in ponds.

Goldfish Care

Tank Size

For a single goldfish, a minimum of 20 gallons (75 liters) is recommended. Every additional goldfish would ideally need another 10-20 gallons. It’s important to note that goldfish produce a significant amount of waste, which requires more substantial water volumes to dilute and process effectively.

How To Set Up Their Tank

Goldfish appreciate a tank with a fine or medium-grained substrate, as they are prone to sifting through it. While they are not demanding about their decorations, smooth rocks, driftwood, and robust plants like Anubias and Java Fern can provide enrichment. Be cautious, as they might nibble on softer plants. Efficient filtration is crucial due to their waste production.

Lighting Requirements

Standard aquarium lighting is suitable for goldfish. It benefits both the fish, by showcasing their vibrant colors, and any live plants within the tank.


Goldfish thrive in slightly alkaline water, so a pH range of 7.0 to 7.5 is ideal.


Goldfish prefer cooler water temperatures. A consistent range between 65°F and 75°F (18°C to 24°C) is ideal. However, they can tolerate temperatures outside this range for short periods.

Water Parameters

Medium water hardness is preferable for goldfish. Regular water testing is vital to ensure levels of ammonia, nitrites, and nitrates are within safe parameters, especially given the goldfish’s propensity to produce waste.

Disease Potential

Goldfish can be prone to various diseases if their environment is not maintained. Issues like ich, fin rot, and swim bladder disease can occur. Quarantining new additions and maintaining water quality are essential preventative measures.

Food & Diet

Goldfish are omnivores and will eat a wide variety of foods. High-quality pellets or flakes should be their staple, but occasional treats of live or frozen foods like brine shrimp, daphnia, or peas (shelled and boiled) can be offered. Overfeeding should be avoided as it leads to poor water quality and health issues.

Behavior and Temperament

Goldfish are generally peaceful and can be quite social. They’re known for their curious nature, often seen exploring every nook and cranny of their environment. Their active and playful demeanor, combined with their striking appearance, makes them captivating pets.

Tank Mates

Goldfish can cohabit with other non-aggressive, cold-water fish. However, mixing them with tropical fish is not recommended due to differing temperature requirements. Other goldfish varieties usually make the best tank mates, but some options like White Cloud Mountain minnows can also be considered.


Breeding goldfish can be a rewarding experience. By raising the temperature gradually and feeding a protein-rich diet, spawning can be induced. Males will chase females around the tank, and once the eggs are laid, it’s advisable to separate the adults as they may eat the eggs. After hatching, fry can be fed infusoria or specialty fry foods until they can handle larger diets.

Goldfish FAQs (Frequently Asked Questions)