Goldfish are an extremely popular type of fish to keep as pets. Although many hobbyists have successfully raised Goldfish, some myths about this fancy fish are persistent. For instance, it is commonly believed that Goldfish live about five years. Actually, if cared for properly, a Goldfish can live to twenty years old. Another myth that must be dispelled is that a Goldfish will grow to fit the size of its bowl. This is also not true and, in fact, Goldfish need more than a bowl as their enclosure. They prefer large tanks that mimic the ponds of their ancestors.

A large tank or aquarium can be a lifetime home for your Goldfish, as some varieties can grow to be adults of one to two feet in length. These fish require a powerful filtration system, as they tend to create a lot of dirt as they go about their business. A large tank also ensures stable water temperature, which is preferable for this type of fish. Careful attention to their diet must be paid, feeding once or twice a day. Goldfish do enjoy a community atmosphere, but like us, do not like to live in crowded spaces. 

a solid orange goldfish swimming to the surface

Goldfish Information

  • Average Length: 4 to 12 inches depending on variety
  • Average Weight: 8 to 12 ounces 
  • Scale Appearance: Translucent
  • Colors: Orange, red, golden, blue
  • Attention Requirements: Low
  • Good tolerance to Heat and Cold: Yes
  • Good Pet: Yes!
  • Good with Other fish species: Yes 
  • Good with Other Goldfish: Yes
  • Suitable for First-Time fish owners: No
  • Training: They can learn a few tricks 
  • Weight Gain: Can become obese if overfed
  • Health Concerns: Generally they are healthy but some may develop swim bladder problems, complications when ammonia levels are high, and death due to drastic water changes.
  • Average Life Span: 10 – 15 years

Physical Appearance of Goldfish 

Goldfish exist in several different colors, but orange and red are the most common colors. The original fish from China had a golden color but which has since changed due to gene mutations. 

The wild Goldfish has only one scale type while the pet varieties have three scale variations. Goldfish have pigment cells called chromatophores which determine the color variation of your pet. 

Goldfish also have guanine chemical deposits on their skin which cause the shiny reflective colors you see on your fish. Probably you didn’t know but goldfish scales are thin, translucent and colorless. The color appearances depend on the amount of guanine on the skin and how deep it’s deposited.

Goldfish are also known to change their color brightness depending on the amount of light available. Expert goldfish pet keepers say that if you switch off the lighting in your fish tank at night, the following morning your fish will appear pale. 

This is actually interesting because Goldfish kept in a pond outdoors appear brighter than the fish kept indoors.

Here are 3 scale types for Goldfish and how they are formed. 

  • Matte

The fish with this scale type have a translucent color appearance without any reflection. 

  • Metallic

The Goldfish with metallic scale types have a translucent and reflective look. The scales of the fish usually appear like polished metal. These Goldfish have one or two color variations depending on the genetic makeup. Most Goldfish have this type of scale. 

  • Nacreous 

The Goldfish with this type of scales have a combination of reflecting and translucent skin. Most Goldfish in this category have more than one color variation of orange, red, blue, and white.

a goldfish with a lot of air bubbles under them

Temperament of Goldfish

Goldfish are peaceful and easy going, but just like other pets, they can become aggressive if they aren’t comfortable within their habitat. In most cases, aggression by Goldfish is directed towards other fish in the aquarium.

The fish can fight each other for space if more than one are placed in a small space. Goldfish love swimming in spacious tanks and playing in the sand. In a tank with limited space, it can cause them to become aggressive.

Another reason that can cause aggressiveness in goldfish is breeding. Male Goldfish are known to be violent during the breeding season. The fish may also fight for eggs in the aquarium because goldfish love eating their eggs before hatching.

But how can you detect signs of an aggressive goldfish in the tank? Here are some of the things to look out for.

  • Fish with missing scales
  • Goldfish with torn lips or fins
  • Signs of rotting on the body of the fish
  • Missing eyes
  • Fish hiding for a long time

Training Goldfish

Did you know that your Goldfish is intelligent and can learn a few tricks? The pet has a memory equal to three months and can easily differentiate colors including the infrared. 

Goldfish also recognize their human caregivers based on the way they get close to the walls of the aquarium if you approach. They won’t actually be able to differentiate your face from that of other humans in the home. 

What actually happens is that goldfish associate humans with food. It’s no wonder the reason the pet moves closer to you expecting some food or a treat.

Amazingly, goldfish can quickly learn how to complete mazes within the tank. So it is possible for you to have a simple maze for your pet to move through.

a white goldfish with orange spots on it

Tank Conditions for Goldfish

Goldfish do alright in cold water with temperatures ranging between 65 and 72 degrees Fahrenheit. They do tend to do much better between 68 and 74 degrees though.  But if your home temperatures are within 65 and 72 degrees Fahrenheit, you don’t need a water heater for the fish tank.  

The best pH for your fish should be between 7.0 and 7.4 such that the water is slightly alkaline and not acidic.

a mostly orange goldfish at the bottom of a fish bowl

Best Tank Mates for Goldfish

The main concern while selecting a tank mate for the Goldfish is that they must be comfortable in the same tropical temperatures that the Goldfish needs. Goldfish generally like to live alone and most Goldfish who have been alone for a year may not like any company. A good start would be to add another Goldfish. 

They can be aggressive towards other Goldfish. If you plan to keep multiple Goldfish together it is best if they are similar in size, otherwise the larger ones might eat the smaller ones. The tank size should also be large enough to give enough space to each fish. Experts recommend having 20 gallons of water for one Goldfish and subsequently add 10 gallons for each goldfish.

They can also live well with other fish species like –

Tank Maintenance

The temperature and pH level inside the tank should be checked regularly. Rapid fluctuations can be harmful to the fish. 

A good filtration system should also be installed inside the tank. Around 10% of the water should be replaced every week. If you miss replacing the water on any of the weeks, then 25% of the water should be replaced in the following week. If you are adding tap water, make sure to treat it with a water conditioner.  

The level of compounds like ammonia, nitrate and nitrite should be checked regularly. If the nitrate level is more than 30 ppm it means you have not changed enough water. The quantity and frequency of water changes will also depend upon the number of fishes and the size of the tank.

a beautiful solid orange goldfish swimming near some aquatic plants
a golden yellow goldfish swimming near aquatic plants

Health Issues

Goldfish can easily contract illnesses from their environment. Here are some of the reasons why your pet could get sick or die.

High levels of Ammonia in Water

Goldfish excrete ammonia which is toxic. Regular water changes helps to keep ammonia levels low within the aquarium. For a new tank, it’s recommended that you carry out weekly water changes. 

When you change out the water it is recommended that you remove and replace 25% of the water in the tank with freshwater.

High concentration of ammonia in your water is hazardous to the health of your fish. If you see your Goldfish start to develop black patches on their skin you will immediately know that you have higher levels of ammonia in your fish tank.  

It’s also important to note that some Goldfish could develop black spots as a genetic mutation in color so that you don’t get confused.  It is best to monitor the ammonia of the water if you see the spots develop only on one fish, but if only one develops the spots it is not something to worry about.

Dry swim bladder/ Constipation

The swim bladder is a sac positioned right above the fish stomach and that connects to the oesophagus. The swim bladder has many blood vessels and helps the fish to gain buoyancy in water. 

An inflated swim bladder allows your fish to float on water while a deflated one enables the pet to swim underwater with ease.  Unfortunately a dry swim bladder affects your fish and could even kill it. 

You can identify signs of a dry swim bladder by observing how fish float on water. Most affected Goldfish will float on their sides. 

To control the problem, you should offer your pet moistened fish flakes. You should also supplement the fish diet with live and gel foods that have high moisture content. 

Uncovered tanks tempting the fish to jump out

Goldfish are experts at jumping from open tanks. You should make sure the tank is properly covered to prevent your fish from jumping out of the tank. 

General Goldfish Care

A Goldfish will live for many years if cleanliness is maintained within its tank. It’s also very important to maintain constant water conditions in the fish tank. A sudden change in water temperatures can shock your fish and kill them. 

Always have water testing kits to ensure that the water conditions remain constant. 

Goldfish placed in a small space release waste at a higher rate compared to other types of fish. The waste could easily kill your fish if not dealt with promptly. Provide a spacious tank for your pet to swim freely and to allow for proper growth. 

Attention Needs of Goldfish

For many children, Goldfish will be their first pet, but Goldfish aren’t the best choice for beginners. Goldfish require large tanks with the minimum size being 20 to 30 gallons. 

For every additional fish you place in the tank, it is highly recommended to add 10 gallons of water. The bigger the aquarium size, the more expensive they get. 

Goldfish are also very messy and require a lot of cleaning especially because they excrete high ammonia levels. It’s expected that Goldfish owners have in place good filtration systems to remove the harmful chemicals.

Not having a good, or even any type of filtration system is the #1 reason why Goldfish tend to die within a week.  Filters keep a safe environment for the fish tank by removing toxic chemicals. If you’re a beginner, it’s very easy to make mistakes that could lead to the death of your fish within days.

Feeding a Goldfish

Goldfish are omnivorous and will eat commercial pellets available in the pet stores. As you feed your Goldfish on commercial pellets, experts recommend soaking the pellets in some aquarium water. Soaking the pellets in some aquarium water prevents the fish from having problems with a dried swim bladder.

Some Goldfish also eat live foods such as bloodworms, insects, and some very finely shredded vegetables.  Quite often a local pet store will have live food for your fish if you want to feed them something different from their usual fish flakes.

It’s also worth noting that Goldfish should only be fed twice daily. Since the pets have very small stomachs, only feed them what they can eat within 3 to 5 minutes. Overfeeding your fish could result in abdominal problems. Leftover fish food can also contaminate the tank.

You only have to throw in the pellets and other treats inside the aquarium.  Your fish will eat them right from the surface.  If you wanted, with patience, your pet could even learn how to eat from your hands.

fish food

Related Questions:

Can I have more than one Goldfish in one tank?

The general rule of thumb when keeping more than one Goldfish in a tank is all about the size of the tank. You should have a gallon of water for every 2 inches of your fish. Having to place a single or two goldfish in a 20 gallon tank seems as though the tank is empty but is beneficial to your pets.

Since Goldfish exist in different varieties, when placing them together in a tank you should observe their fins. Goldfish that have similar fins are compatible and can coexist peacefully but generally all goldfish varieties can live together.

Some goldfish varieties such as the Lionhead, Bubblehead, and Ranchu have double fins which are bulkier making them slower. Single finned Goldfish such as the Comet are fast swimmers. Placing a faster and a slower goldfish together could lead to competition for food.

Are Goldfish good with other fish species?

It’s possible to place your Goldfish with other fish species as long as you make sure they can all survive in similar water conditions. You also have to ensure that the fish don’t prey on each other. 

What are some basic facts about Goldfish?

Goldfish originated from China over 1,000 years ago but today are kept as pets by people all over the world. In America, Goldfish is the most popular pet fish. 

Goldfish are freshwater fish that take in oxygen using their mouths because they don’t have lungs. The fish after taking oxygen from water, then releases the water out of their bodies using openings on their gills.

Did you also know that Goldfish don’t have eyelids? It’s no wonder the reason why the pets have bulgy eyes that don’t close even while sleeping.

While Goldfish and Koi look similar to many people they are actually different fish.

There is a popular misconception that Goldfish never stop growing.  While this may be true in the wild, Goldfish in an aquarium rarely get larger than 6 inches.

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