Common Goldfish: Profile, Care, Diet, Tank Mates & More

Common Goldfish
Common Goldfish
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: March 14, 2024
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The common goldfish, a well-liked species among freshwater aquarium enthusiasts, is a member of the Cyprinidae family and originates from East Asia. Their striking hues and elegant maneuvers make them an outstanding enhancement for any domestic aquarium. These freshwater dwellers earned their reputation for their sturdy nature and flexible adaptability, appealing to both seasoned aquarium keepers and beginners. If you’re thinking about beginning a new aquarium or just want to introduce diverse elements to your current freshwater exhibit, the common goldfish’s enchanting beauty and charisma are certainly going to enthrall you.

Article Summary

  • Common goldfish can grow up to 12 inches in length, and some variations may have unique features like comet goldfish with a longer body or bubble eye goldfish with fluid-filled sacs under their eyes.
  • They have an omnivorous diet and should be fed high-quality pellets, flakes, or gel food formulated for goldfish.
  • Common goldfish are generally peaceful but can become competitive during feeding; tankmates should be similar in size, prefer cooler water temperatures, and avoid aggressive species.

Common Goldfish Appearance

Common goldfish, also known as fantail goldfish, are easily recognizable due to their distinctive bright orange or yellow coloration. These vibrant hues make them stand out in any aquarium. With a long, slender body and a forked tail, common goldfish have an elegant and graceful appearance.

One of the fascinating aspects of common goldfish is their potential for growth. They can reach lengths of up to 12 inches, making them quite sizable compared to other fish species commonly kept in home aquariums. This substantial size adds to their visual appeal and makes them a captivating addition to any aquatic environment.

When observing a common goldfish, you may notice additional physical characteristics that vary among different types of goldfish. For example, comet goldfish have a longer body with a single tail fin that trails behind them like a comet’s tail. Bubble eye goldfish have fluid-filled sacs under their eyes that create the appearance of bubbles.

Common Goldfish Side View
Common Goldfish Side View

Another interesting feature is the presence of white spots on some varieties of common goldfish. Known as “calico” coloration, these specks add an element of uniqueness and beauty to their overall appearance.

In terms of fins, common goldfish typically possess a dorsal fin located on their back. This fin helps with stability and maneuverability while swimming through water.

To keep these magnificent creatures healthy and happy, it’s important to provide them with proper care and nutrition. Feeding them high-quality flakes specifically formulated for goldfish is essential for their well-being.

Tank and Water Requirements

To keep common goldfish healthy and happy, it’s crucial to provide them with the right tank and water conditions. Here are some important points to consider:

Spacious Tank Size

Common goldfish need plenty of space to swim around and grow. It is recommended to have a spacious tank with at least 20 gallons of water per goldfish. This ensures that they have enough room to move and prevents overcrowding, which can lead to stress and poor health.

Filtration System for Water Quality

Maintaining good water quality is essential for the well-being of your common goldfish. These fish produce waste that can quickly accumulate in the tank, leading to ammonia buildup and harmful bacteria growth. To prevent this, invest in a reliable filtration system that can effectively remove waste particles, toxins, and excess nutrients from the water.

Optimal Water Temperature

Common goldfish prefer cooler water temperatures ranging between 65°F and 72°F (18°C-22°C). Avoid exposing them to extreme temperature fluctuations as it can stress the fish. Use a reliable aquarium thermometer to monitor the water temperature regularly.

Regular Water Changes

Regular partial water changes are necessary to maintain optimal water quality for your common goldfish. Aim for weekly or bi-weekly water changes of about 25% of the total volume in the tank. When performing a water change, make sure you treat tap water with a dechlorinator before adding it to the aquarium.

Community Tank Considerations

If you plan on keeping other fish species with your common goldfish in a community tank, be mindful of their compatibility and specific care requirements. Some fish may have different temperature preferences or may be more aggressive towards goldfish. Research thoroughly before introducing any new species into the same tank.

Remember, providing an appropriate tank size and maintaining good water quality are essential factors in ensuring the health and happiness of your common goldfish.

Common Goldfish Health

Common goldfish, like any other living creature, require proper care and attention to maintain their health. Here are some important points to consider when it comes to the health of your common goldfish:

Prone to Swim Bladder Disease

Overfeeding and poor water quality can lead to swim bladder disorders in common goldfish. These disorders affect the fish’s ability to control its buoyancy, causing it to float upside down or sink to the bottom of the tank.

To prevent swim bladder disorders in your goldfish, it is important to feed them an appropriate amount of food and avoid overfeeding. Additionally, ensure that the water in the tank is clean and well-maintained. By following these guidelines, you can help keep your goldfish healthy and reduce the risk of swim bladder issues.

Fungal and Bacterial Infections

Dirty water can also contribute to fungal and bacterial infections in common goldfish. These infections can manifest as white patches or sores on the fish’s body.

To prevent fungal and bacterial infections in your fish tank, it is important to regularly clean the tank and maintain good water quality. Additionally, it is crucial to monitor your fish for any signs of infection and seek appropriate treatment if necessary.

Sensitivity to Ammonia and Nitrate Levels

Common goldfish are sensitive to ammonia and nitrate levels in their environment. High levels of these compounds can be harmful to their health. To ensure the health of your aquatic environment, it is important to regularly test the water parameters using appropriate testing kits.

By monitoring ammonia and nitrate levels, you can take necessary steps such as partial water changes or adding beneficial bacteria products to maintain optimal conditions. This will help prevent any sensitivity issues that may arise from high ammonia or nitrate levels.

By taking these precautions, you can help prevent common health problems associated with keeping common goldfish as pets. Remember that providing a clean and suitable environment is essential for their wellbeing.

Common Goldfish Diet

Common goldfish have an omnivorous diet, which means they eat both plant matter and protein-based foods. It’s important to provide them with a balanced and varied diet to keep them healthy and happy.

Primary Food

Opt for high-quality pellets, flakes, or gel food specifically formulated for goldfish. These commercial fish foods are packed with essential nutrients that support their growth and overall well-being. Look for options that contain a good balance of proteins, fats, carbohydrates, vitamins, and minerals.

Supplementing With Fresh Vegetables

In addition to commercial fish food, it’s beneficial to supplement your common goldfish’s diet with fresh vegetables. Peas and lettuce are excellent choices as they are easily digestible and provide additional fiber. Before feeding them to your goldfish, make sure to blanch the vegetables by briefly boiling or steaming them until they become soft.

Consider Adding Live Food or Algae Eaters

To mimic their natural diet in the wild, you can occasionally offer your common goldfish live food such as brine shrimp or bloodworms. This provides them with a source of protein that they would typically consume in their natural habitat. Introducing algae eaters like snails or shrimp into the tank can help control algae growth while providing some variety in their diet.

Temperament and Tankmates

Common goldfish are generally peaceful but can become competitive during feeding time. They can coexist with other goldfish species and some cold-water fish like weather loaches. However, it is important to consider the compatibility of tankmates with common goldfish.

Suitable Tank Mates

Goldfish are social and can generally coexist with various tank mates, but there are some considerations to keep in mind. Here are ten suitable tank mates for common goldfish.

Bristlenose Plecos

Common goldfish are compatible with bristlenose plecos due to their peaceful nature and ability to coexist in the same tank. Both species have similar water temperature and pH requirements, making it easier to maintain suitable conditions for both fish. Additionally, common goldfish are not known to be aggressive towards plecos, allowing them to live harmoniously together. However, it is important to ensure that the tank is large enough to accommodate both species, as plecos can be territorial.

Chinese Algae Eaters

The common goldfish is compatible with Chinese Algae eaters because they both have a similar diet and can help control algae in the tank. The goldfish are known for their ability to produce a lot of waste, which can contribute to algae growth. Chinese Algae eaters can help to keep the tank clean by consuming the algae, reducing the chances of an overgrowth.

However, it is important to note that as the Chinese Algae eaters age, they may become more aggressive and potentially bother the goldfish. Therefore, it is important to monitor their behavior and provide enough space and hiding spots in the tank to ensure a harmonious coexistence.

Dojo Loaches

Common goldfish are compatible with dojo loaches due to their similar bottom-dwelling behavior. Both species prefer to spend most of their time near the substrate of the tank, making them suitable tank mates. Additionally, dojo loaches are known for their playful behavior, which can provide entertainment for goldfish. This compatibility allows for a harmonious coexistence in the aquarium, creating a visually appealing and dynamic environment for both species.

Ghost Shrimp

Common goldfish are generally compatible with ghost shrimp due to their peaceful nature. Ghost shrimp can coexist with goldfish without causing any harm or aggression. However, it is important to note that larger goldfish may view ghost shrimp as potential prey and may try to eat them. Therefore, it is recommended to keep ghost shrimp with smaller or juvenile goldfish to ensure their safety.


Koi and common goldfish are compatible tank mates because they are closely related species. Both koi and goldfish belong to the same family, Cyprinidae, and share similar care requirements. They have similar diets, water temperature preferences, and can tolerate similar water conditions. Additionally, koi and goldfish have similar swimming patterns and behaviors, making it easier for them to coexist in the same tank or pond. However, it is important to ensure that the tank or pond is spacious enough to accommodate the size and activity levels of both species to ensure their optimal health and well-being.

Other Goldfish

Goldfish Tankmates
Goldfish Tankmates

Goldfish are compatible with other goldfish because they are social creatures that thrive in the company of their own kind. When kept with other goldfish of similar size and variety, they can engage in natural behaviors such as schooling and playing together. This social interaction not only provides mental stimulation but also promotes overall well-being. However, it is important to ensure that there is enough space in the tank to prevent overcrowding, as this can lead to stress and health issues.

Rosy Red Minnows

Common goldfish and rosy red minnows are compatible tank mates due to their similar hardy nature and size. Both species can tolerate a wide range of water conditions and are able to adapt well to different environments. Additionally, rosy red minnows are known for their fast swimming abilities, which can add a lively and active element to the tank.

However, it is important to note that the size of the rosy red minnows should be large enough to prevent them from being considered as food by the goldfish. Overall, the combination of common goldfish and rosy red minnows can create a harmonious and visually appealing aquarium setting.


Common goldfish can be compatible with some types of snails due to their peaceful nature and similar water temperature requirements. Goldfish are generally not aggressive towards snails and will not harm or harass them. Additionally, snails can help keep the tank clean by consuming excess food and algae, which can benefit the goldfish by maintaining a healthier and cleaner environment. However, it is important to monitor the snail population to prevent overpopulation, as this can lead to water quality issues.

White Cloud Mountain Minnows

Common goldfish and white cloud mountain minnows are compatible tank mates due to their peaceful nature. Both species generally get along well and can coexist without any major issues. However, it is important to note that white cloud mountain minnows prefer cooler water temperatures compared to goldfish. Therefore, it is crucial to ensure that the tank’s temperature is suitable for both species to thrive and remain healthy.

Always consider the size of the tank, water parameters, and the specific needs of each species when selecting tank mates. Additionally, monitor the interactions between the fish to ensure a harmonious community.

Compatibility and Size

Tankmates for common goldfish should be similar in size to prevent any aggression or bullying. It is best to avoid pairing them with smaller tropical fish that may be seen as prey. Instead, opt for larger fish that have a similar temperament and size requirements.

Temperature Requirements

Since common goldfish are cold-water fish, their tankmates should also prefer cooler water temperatures. Avoid adding tropical fish that require warmer water conditions, as this could lead to stress or health issues for both the goldfish and its tankmates.

Aggressive Fish

It’s crucial to steer clear of aggressive fish species when choosing tankmates for common goldfish. Aggressive fish can pose a threat to the well-being of the goldfish and disrupt the overall harmony in the aquarium environment.

Social Animals

Common goldfish are social animals and thrive in groups. Consider keeping them with other common goldfish, like a comet goldfish, or even different types of fancy goldfish. This will provide companionship and stimulate natural behaviors among the fish.

Breeding Common Goldfish

Breeding common goldfish can be an exciting and rewarding experience for fish enthusiasts. The breeding season typically occurs during springtime when the water temperature starts to rise. During this time, male goldfish develop white breeding tubercles on their gill covers and pectoral fins.

Females play a crucial role as they release eggs that are fertilized externally by the males. These eggs are adhesive and will stick to various surfaces in the aquarium or pond. It’s important to provide suitable spawning materials such as plants or spawning mops for the eggs to attach to.

A Closer Look at Goldfish Eggs
A Closer Look at Goldfish Eggs

Once fertilized, the eggs will hatch within a few days, releasing tiny fry into the water. These fry are extremely fragile and require special care. Providing them with proper nutrition is essential for their growth and development. Feeding them commercially available liquid fry food or freshly hatched brine shrimp can help ensure their survival.

It’s worth noting that not all common goldfish breeds are capable of reproducing naturally due to genetic modifications or deformities. For example, genetic dwarf goldfish may have difficulty breeding due to physical abnormalities. If you’re specifically interested in breeding goldfish, it’s important to choose healthy specimens from reputable sources.

Many breeders prefer outdoor ponds for breeding common goldfish as they provide a more natural environment conducive to successful reproduction. Outdoor ponds offer ample space for multiple fish and allow for better control over water conditions.

Frequently Asked Questions

Are common goldfish friendly?

Common goldfish are generally considered friendly and social. They can recognize their owners and may even swim up to greet them. However, individual personalities can vary, and proper care and handling contribute to their friendliness.

What is the most common goldfish?

The most common goldfish is the “Common Goldfish” (Carassius auratus), often recognized by its streamlined body, single tail fin, and vibrant orange coloration. This variety is widely popular and easily recognizable in both ponds and aquariums.

How long does a common goldfish live?

Common goldfish have the potential to live for several years, with an average lifespan ranging from 10 to 15 years. Proper care, a suitable environment, and a balanced diet contribute significantly to their longevity.

What is the difference between fancy and common goldfish?

The main difference between fancy goldfish and common goldfish lies in their physical characteristics. Fancy goldfish, such as the Fantail or Oranda, have distinctive features like double tails, bulging eyes, and unique body shapes, while common goldfish have a more streamlined appearance with a single tail fin.

Will goldfish eat guppies?

Goldfish are generally omnivores and may eat smaller fish, including guppies. While they are not aggressive hunters, the size and temperament of the goldfish, as well as the size of the tank, can influence whether they coexist peacefully with guppies. It’s essential to monitor their interactions and provide adequate space to reduce the likelihood of predation.

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