Who hasn’t kept goldfish at some point? For many of us, goldfish were our introduction to the aquarium hobby. Here are 10 common misconceptions about goldfish.
Number 1: Goldfish Can Be Kept in Bowls
While goldfish are hardy fish capable of surviving in a range of conditions, a bowl is really an ill-suited home for them. Bowls lack proper filtration, aeration, water volume for the dilution of waste and space to grow. Goldfish require large aquariums for their long-term care and survival, as goldfish can grow quite large, depending on the variety. The common goldfish are among the largest and are capable of reaching over 45cm and 4.5kg. Even the smallest varieties can reach between 10 and 20cm, making them more suitable for a 75 litre (20-gallon) or larger aquariums. Due to the goldfishes’ large size, proper filtration and water changes are a must. For larger goldfish, such as the common goldfish or comet, an outdoor pond is really the best option.
Number 2: Goldfish Only Grow to the Size of Their Tank
While there is an element of truth to this, it is not as innocent as it sounds. When properly cared for, goldfish will not stop growing. Most fish are indeterminate growers, meaning that, unlike humans, they grow until they die. The only reason for a fish to stop growing is poor water quality and improper care. In smaller aquariums or bowls, water quality is typically very poor. With little or no filtration and infrequent water changes, goldfish suffer. The stunting that results is not a good thing. It is a sign of ill health and stunted fish often become deformed and die at a young age. As already stated goldfish grow very large, so it is important to take into account the eventual size of your fish and make sure that you can provide it with the proper care. (For more information see: Water Changes and Fish Growth)
Number 3: Goldfish Have a Three-Second Memory
It has long been said that a goldfish can be kept in a bowl because their three-second memory never allows them to get bored or tired of seeing the same thing. In other words, by the time they swim around the bowl, they have already forgotten where they started. This is pure myth and probably came about purely as justification for keeping them in bowls in the first place. Goldfish are capable of remembering things for very long periods of time—at least three months. Goldfish also have a sense of time and will learn a routine. The excited behaviour some individuals exhibit in the morning before we even get the food canister out is evidence of this. Goldfish are also quite trainable. They can learn to swim through hoops, ring bells, and pull levers for food. In a lever experiment involving goldfish, they were even able to realize within an hour that if the lever stopped producing, it wasn’t worth pulling anymore.
Number 4: Goldfish Are Short-Lived
Goldfish are actually some of the longest-lived fishes you can purchase. They are capable for living several decades under the right conditions. The record age for a goldfish is 49 years of age. The reason why so many die at a young age is due to poor water quality and inappropriate living conditions. If goldfish are a fish you wish to keep, prepare yourself for a long-term commitment.
Number 5: Goldfish and Koi Are the Same Species
While both are closely related and are even capable of hybridization, they aren’t the same fish. Although both belong to the family Cyprinidae, they are different species. Koi are Cyprinus carpio while goldfish are Carassius auratus.
Number 6: Each Kind of Goldfish Is a Different Species
Similar to how all domestic dogs are the same species, so are all domestic goldfish. All the strains you see in the fish shops—fantails, lionheads, ryukins, comets, orandas, bubble eyes, etc. are all the same species.
Number 7: Goldfish Require Cold Water
While goldfish are capable of surviving in very cold conditions, they have no problem surviving in warm conditions as well. This is evidenced by the climate of their native habitat in central Asia, which is a subtropical region where goldfish not only endure cold winters but also very warm summers. Simply examine all the places goldfish have been introduced to in order to see just how adaptable they are, such as Brazil, Costa Rica, Hawaii, Madagascar and Australia.
Number 8: Goldfish Cannot Be Kept with Tropical Fish
While many tropical fish won’t work with goldfish for a variety of reasons, there is no reason why some species cannot make suitable tank mates. Goldfish are able to live in a wide range of temperatures, so some overlap does exist. It is, however, important to keep goldfish with species that require similar habitats and conditions.
Number 9: Goldfish Are Herbivores
Goldfish are actually omnivores, eating both plant and animal material. While they consume a large amount of plant material, they will also eat invertebrates and even smaller fish species. Larger goldfish have been known to eat smaller tank mates. A proper diet for captive goldfish should include both plant and animal material. Goldfish will happily graze on blanched lettuce, cucumber, oranges, and soft-leaved aquarium plants such as duckweed and anacharis. In regard to animal-based foods, the various freeze-dried and frozen invertebrates available on the market make nice goldfish treats. A high-quality goldfish pellet should be the fish’s staple diet.
Number 10: Goldfish Make Good Feeder Fish
Because they are so abundant and easy to reproduce, common goldfish have become very popular as feeder fish, but they are far from ideal as feeders. They have a particularly high fat content. They also contain large amounts of thiaminase, which destroys vitamin B1 (thiamin). An animal that consumes too much thiaminase will develop a B1 deficiency, leading to illness and death. If you have a predatory fish and want to use feeder fish, your best choices are properly quarantined or home-bred tropical species.
Under the right conditions, goldfish are a fantastic species of fish to keep. They are hardy, adaptable and long-lived. When properly cared for, goldfish are a great choice for any fish-keeper regardless of their level of experience. I encourage everyone to share this information with others and to do some research of their own, and maybe someday we can finally put all these goldfish myths to rest.