There are many types of goldfish. All belong to the same species, Carassius Auratus. They breed very easily and can often live more than ten years. These fish come in single tail varieties as well as split tails which are fancier. The most popular of these are the comet, shubunkin and sarasa.

Generally, they have an orange-red color making them easy to spot in the water garden. They usually do not grow beyond 15” and will feed from the bottom until “trained” to recognize the person feeding them.


Koi, Cyprinus Carpio, are the gems of the water garden. Here are some facts about this spectacular fish:

  • First developed in Japan over 2000 years ago
  • Used primarily as a food source until the late l9th Century
  • Individual fish have been carbon dated at over 250 years old
  • Will grow to a length of 2′ in ornamental ponds
  • Are cold blooded- Can live in a wide range of temperatures
  • Are produced mostly in Japan, Israel and here in the USA
  • The fish are produced with a straight fin or butterfly fin
  • The most popular varieties are Kohaku, Sanke & Showa
    • Kohaku- are white koi with a red or hi marking
    • Sanke – Japanese for tri-colored. The three colors being white
      red and black
    • Showa – a black koi with red and white markings

How do I tell the difference between a koi & goldfish?

  1. Size of fish
  2. Color of fish
  3. Koi have barbels

Feeding Goldfish & Koi

Goldfish & Koi are bottom feeders. They can be trained to come and eat from the surface by using a floating food in either pellet or stick form. These fish benefit from a diet with a protein level of 30-40%. Here are some facts on feeding goldfish and koi:

  • Because these fish are ectothermic, they will actively feed at temperatures above 50 degrees.
  • A good food will provide a source of proteins, fats, carbohydrates, vitamins and minerals which are essential for fish to remain healthy.
  • Color enhancers, like spirulina, carotene and marigold extract are added to foods to enhance the colors on koi & goldfish.
  • Check the main ingredient in your fish food. The protein in the food should come from an animal (like fish) rather than a plant. The better foods use fish meal or anchovy as their protein base, making them more expensive.
  • During the fall and early spring when water temperatures are low, fish should be fed a food high in carbohydrates and low in protein. These foods pass through the fish quickly, reducing the risk of the food lingering in the gut, causing severe problems.
  • To train fish to come to you and eat from your hand, you should feed from the same spot in the pond each day at about the same time. Food should never be broadcast onto the pond. All food should be placed into the pond via your hand. The fish will quickly realize that you are there to feed them (and not eat them) and rush to your hand for food.
  • The general rule of thumb is to feed the fish what they will eat in three to five minutes. This can be done once or twice a day. Do not leave uneaten food in the pond or let the food travel into the skimmer box.

Breeding Goldfish & Koi

Goldfish & Koi will breed in your pond when water temperatures reach above 60 degrees. Goldfish will breed two-three times a year and koi will breed once. Breeding usually takes place after a rain storm.

  • Koi need to be over 10 inches in length to be sexually mature.
  • It is difficult to sex koi and goldfish. Male fish have very straight lines, while females have wider “hip” areas. Male fish develop breeding tubercles on the pectoral fins.
  • In most cases, when koi and goldfish are mixed you will not hatch any koi fry. The goldfish will eat all of the koi eggs, although goldfish eggs will not be eaten by other Goldfish or Koi.
  • Spawning ropes can be added to the pond to collect the eggs and then moved to a nursery tank to hatch the eggs.
  • It will take three to five days for koi and goldfish eggs to hatch.
  • Although koi show their colors early in development, it might take goldfish up to two years to “color up.”

What happens to the fish in the winter?

Fish are cold blooded. Their metabolism is directly related to water temperature. When water temperatures drop, the fish become dormant. They do not eat, they do not swim, and their breathing is very shallow. They are conserving energy. The fish do not eat during the winter months. You must keep a small hole in the ice using an aerator. If this is not enough to keep the hole open use a pond deicer to keep the hole open. Cooper’s has de-icing & heating products for the wintertime.