Differences between Koi and Goldfish

Koi and goldfish are a popular combination for coexistence in backyard ponds. Both share an ancestor in the carp, are docile, hardy, and have similar environmental and dietary needs. However, your Blue Ridge Koi and Goldfish are distinct species and differ in several ways, including size, shape, coloring, lifespan, and cost.

Size

Size is the most noticeable difference between koi and goldfish. Koi tend to be much larger, averaging between 20 and 25 inches long, potentially becoming even larger in the right pond environment. Goldfish typically grow between eight and 10 inches, though they can surpass 12 inches with the right genetics and optimal conditions.

Shape

Koi are longer and leaner than goldfish, which are relatively short and stout. Koi have an elongated, torpedo-shaped body similar to their carp ancestors, with a downward-facing mouth and whisker-like barbels. Goldfish have wider and rounder bodies, with front-facing mouths and round jaws. Some goldfish have bulging eyes, while the koi’s eyes are spherical and flat. The dorsal fin and tail on koi are connected and on goldfish appear separate. Goldfish have two sets of paired fins, three sets of single fins, and can be single- or double-tailed. The only koi with comparable traits is the butterfly variety. This koi has long, flowing fins in various colors and patterns.

Coloring

You can find koi and goldfish in a basic pallet of orange, red, black, white, and yellow. For koi, that’s just a starting point. The color and pattern options can seem endless, with the additions of green, blue, brown, gray, silver, and gold colors that are possible to spot across koi varieties. Goldfish offer more geometric variation than koi, with many different body shapes, fin types, eye configurations, and tail lengths. Koi also have a variety of scale patterns, while goldfish are either metallic, nacreous, or matte.

Lifespan

Both koi fish and goldfish reach maturity at two to three years old, with the average lifespan for a goldfish at about ten years. A koi can easily live two to three times longer, with a lifespan that ranges from 25 to 35 years. The oldest known koi is said to have lived for 226 years, whereas the oldest known goldfish lived for 43.

Cost

While the price of koi and goldfish can range significantly for each, koi generally cost more and have the potential to be extremely expensive. An individual koi can sell from as little as $10 to upward of $20,000 depending on its variety, size, color, pattern, and lineage. A goldfish can sell for less than a dollar, up to several hundred dollars or more.
In a well-maintained pond environment, pond goldfish and koi should have no issues living harmoniously.