For someone who has been a victim of this long-running carp cousin confusion, I will make sure you don’t fall prey to your local pet shop employee’s cunning marketing skills (like I did) and get an unbiased review of the difference between Goldfish and Koi.
Before proceeding, I will tell you one thing: both pond-fish options are amazing creatures. Which one to keep depends on your requirements and your ability to tell the difference between either.
Koi Fish (Cyprinus Carpio) – A Brief Introduction
Also known as Nishikigoi, the koi fish originates from Japan, offering several colors and patterns across its varieties. It is a color variant of the Amur Carp. There’s a near rainbow and more in the red, orange, yellow, green, blue, brown, black, white, gray, silver and gold colors that are possible to spot across koi varieties.
This species has quite an aesthetic appeal that makes it stand out. Maybe this is why it is so popular among hobbyists for pond fishing.
Goldfish (Carassius Auratus) – A Brief Introduction
Native to China, pond goldfish are members of the Carp family (Prussian carp) and have been bred for thousands of years.
The species is quite personable, so much so that it can recognize its owners! Its interactive nature was the reason I bought it without any second thoughts.
Koi Fish VS Goldfish: Major Differences
To make an informed decision about whether Goldfish or Koi is the right choice, you’ll need to consider the needs of these two species.
Both species come with their requirements, which we have outlined below.
Pond Size Requirements
Firstly, the myth that fishes grow according to the size of their surroundings is untrue. Their size is entirely based on genetics.
Koi can easily grow up to 3 feet long, while most Goldfish tend to grow up to 7 to 8 inches.
With size augmentation, more water is also required. A Koi fish requires at least 250 gallons, and if it’s an active reproductive fish, then, at least 500 gallons even in a small pond.
So, if you plan on building a smaller-sized pond, opt for the Goldfish. On the other hand, if you have at least 500-1000 gallons of water available, you can go for an adult koi, which thrives in larger koi ponds.
Extra Advice: If you have a tank, then don’t purchase Koi!
Lifespan
In the right conditions, Koi fish will live longer, with an average lifespan of 20 to 30 years. I have witnessed people pass down Koi through multiple family generations.
According to my research, a Koi named Hanako (Japanese for Flower Girl) reportedly died at age 226 in 1977 (although some experts doubt the credibility of that claim). On the other hand, many reports suggest that the oldest goldfish’s age was 45.
So, if you are ready for a lifelong mate and don’t get bored (which some people do for some reason), then go for a Koi; otherwise, play safe and get a Goldfish.
Cost
The cost of goldfish and koi is very important for fish hobbyists, especially for those on a budget, as it can vary significantly per fish.
A Koi fish can weigh heavy on the pocket. These fish are a high-end product for obvious reasons.
According to my market research, only the small Koi fish cost under $20, while the adults cost more than $350 (personally, I wouldn’t go for such an expensive option as a beginner).
I even read somewhere that the most expensive Koi was sold for $2.2 million. But don’t worry—you don’t need to spend a lot of money if it’s not your thing (I don’t even think that is wise, especially as a newbie).
The good news is that Goldfish are comparatively affordable. All you need to spend is $10 or less. Oh, and don’t worry— Goldfish typically come in various colors and patterns that will also increase the overall aesthetics of your pond environment.
Physical Features
Koi are distinctive species with elongated, torpedo-shaped bodies similar to those of their common carp ancestors. They have a downward-facing mouth to aid them in foraging. Koi also have a variety of scale patterns, while goldfish have front-facing mouths with rounded underjaws. Their scale patterns are either metallic, nacreous, or matte.
Goldfish have a rounder body shape, more like a sphere. I have seen Goldfish with big, goofy, and bulging eyes. Koi, however, do not have such features.
Koi will have these barbels that resemble whiskers, while Goldfish don’t posses any such physical feature.
Koi have a connected dorsal fin and tail, and Goldfish have two sets of paired fins and three sets of single fins.
Keep an eye on these details, and you will have no problem whatsoever.
Filtration
Both Koi and Goldfish tanks require filtration. So, remember to purchase a bigger pond filter that can manage the entire pond’s volume. From what I have seen, a Goldfish makes more mess than a Koi.
If you want to pet a Goldie, make sure that a proper filtration system is present.
Can You Keep Koi Fish and Goldfish Together?
If you still can’t decide, keep Koi and Goldfish together.
And don’t worry. None of the species will hunt down each other (at least mine doesn’t). Feed them on time, and they will live together without causing serious problems.
Will Reach Maturity At The Same Time
A good factor for keeping them together is that they reach maturity at the same age (given that they both are of the same age, too). Both koi fish and goldfish reach maturity at two to three years old, which means no one will overpower the other due to age.
Can Cross-Breed Together
Did you know? Even though Koi and Goldfish are distinct species, they can still cross-breed on rare occasions and produce offspring. So, if you are a pond owner who wants to become a mixed breeder, buy both.
Will Reach Maturity At The Same Time
So, Which One Are You Choosing?
Now that we’ve covered the differences between Koi and Goldfish, which one will you prefer?
I know this is a tough choice, but remember one thing: Make a choice that you can commit to. No pet deserves to be abandoned because of our erroneous and hasty decisions!
