From the Foreword by Richard E. Hess

Goldfish have enchanted mankind for over a thousand years. Their variety of shapes and colors and their graceful movement through the water make them living works of art, and their tameness makes them enjoyable pets; no wonder that people have always found pleasure in collecting them. Today the passion for goldfish collecting is greater than ever, and all over the world the fraternity of collectors grows day by day.

This book is the culmination of research compiled by dedicated experts in their fields. I believe it is the finest, most accurate, and most complete gathering of information about goldfish that has ever been assembled in one source. I'm greatly indebted to my great friend and coauthor, Dr. Erik Johnson, for his expertise in and his dedication to the field of goldfish and Koi health. His persistent research to find and develop new techniques to keep our goldfish healthy is always on the cutting edge, and his section on goldfish health, which makes up Part 1 of this book, will not only be of tremendous help and interest to hobbyists but is a major contribution to the professional literature.

We were fortunate to gain the cooperation of world-renowned goldfish photographer Fred Rosenzweig. Fred is a creative and sensitive photographer, and his stunning photography presents each fish at its best. Fred has spent decades photographing the finest specimens of every goldfish variety, and the fruits of his efforts speak for themselves in these pages.

My thanks go to Jackie and Louis Chan, too, for sharing with us their unique professional knowledge of choosing high-quality goldfish. The Chans are the proprietors of the Tung Hoi Aquarium Company in Hong Kong, and have a vast, and in English as yet untapped, knowledge of fine goldfish. Goldfish originated in China, and China is the main exporter of fancy goldfish today. With a thousand-year tradition of goldfish keeping, collecting, and appreciation, our Chinese "mentors" have much to teach us, and the Chans' essay is a unique look at the Chinese aesthetics of goldfish. This is the first time anything like this has been published in English.

From Chapter 1: Goldfish Keeping and Husbandry

The goldfish belongs to the Cyprinid class of fish and is scientifically referred to as Carrassius auratus. It is unparalleled as an ornamental fish, with more colors and body types than any other species. Hundreds of varieties of goldfish have been bred, and many of them are described in detail in other sections of this book.

Goldfish may be one of the hardiest of ornamental fishes, too; they can withstand temperatures as low as thirty-three degrees Fahrenheit and as high as the low hundreds. Goldfish can also withstand very poor water quality for long periods of time if other conditions are acceptable. They are not especially fussy about their diet and they are not aggressive. If well kept they may live many years. In Asia, their place of origin, they have been kept and bred in ponds and tubs without high-tech equipment for centuries.

The modern goldfish hobby ranges from a tank of pet fish purchased at the local fish store to the breeding and showing of pedigreed champions of the rarer varieties, "living jewels" that can be a source of great pride and satisfaction to their owner. But regardless of where you fall on this scale and what variety of goldfish you keep, the requirements for keeping goldfish alive and healthy are very similar.

Housing
Goldfish may be housed in containers of just a few gallons on up to lakes and pools of many thousands of gallons. As a simple rule of thumb, you should provide at least ten gallons for each mature fish, and more for especially large varieties.

Most hobbyists house their collections of ornamental goldfish in aquariums. Goldfish are large and relatively messy fish, producing considerable quantities of bodily wastes. The larger the aquarium you choose for your collection, the better your results will be. This bears repeating: Get the largest tank you can afford if you want the best possible results with your goldfish. Large tanks not only provide more space and oxygen, but also more stable water conditions.

Of course, goldfish can be kept outdoors in ponds or other containers as well—throughout the year in mild climates. Ponds present their own set of advantages and disadvantages. They offer natural food and light, which often results in larger, more brightly colored goldfish. Because ponds are generally larger than aquariums, they also tend to have more stable water chemistry. But they also present a challenge in both disease and predator management, because the hobbyist has less control of the aquatic environment.

Lighting
Lighting has several effects on fish that can contribute to your success or failure in keeping goldfish. Anyone who is experienced in this hobby will agree that full-spectrum illumination or, better yet, sunlight will enhance and improve skin condition and color in goldfish. Full-spectrum lighting with sufficient intensity and spectrum will also stimulate the growth of healthy green algae on the inner surfaces of the aquarium. Algae benefit the fish in numerous ways including: (1) providing edible phytoplankton for the fish to consume; (2) providing for the reduction of nitrate in the environment; (3) raising dissolved oxygen by photosynthesis during the photo-period; and finally, (4) the algae layer is slick and protects and cushions the fish when they come into contact with the aquarium sides. I strenuously encourage the hobbyist to allow as much sessile green algae to remain on the ornamentation and sides of an aquarium as is aesthetically tolerable.

Lighting also provides the fish with certain metabolic capabilities. Without a full-spectrum light source such as natural sunlight or full-spectrum fluorescent bulbs, the fish will not be able to activate vitamin D in their skin cells and will eventually suffer calcium abnormalities, which may stunt growth or depress the immune system.

Darkness is just as important as lighting. Though they do not close their eyes, fish require sleep, and a lack of sleep contributes to the cumulative effects of chronic stress. Fish that are deprived of a natural cycle of light and dark do not perform as well as fish that are allowed to sleep in darkness. Indeed, fish deprived of darkness still sleep, although they do not derive anything near the benefits that fish with a night-and-day cycle do. The best light cycle is sixteen hours of bright light followed by eight hours of darkness. The longer photoperiod will ensure a healthy carpet of green algae and, therefore, lower nitrate levels, which will be discussed in detail later.

Temperature
The temperature at which we should house our goldfish collections is the subject of debate. While it's true that goldfish of most varieties are extremely adaptable to a wide range of temperatures, there is considerable evidence that goldfish do best in water in the mid to high seventies. This temperature range has several clear advantages.

First, it ensures that the water still carries sufficient oxygen. Water warmer than this carries far less oxygen.

Temperatures in the seventies also ensure adequate function of the nitrifying bacteria in the biological filter. Colder temperatures jeopardize the efficiency and capability of the nitrogen cycle.

Since goldfish are "cold-blooded" animals (poikilotherms), this temperature range ensures the proper functioning of fish metabolism and normal levels of activity without unduly increasing their oxygen demand.

Different varieties of Goldfish also demonstrate different degrees of adaptability to temperature. The hardiest varieties, including Comets, Shubunkins, and Wakins, will survive winter in North America unless the pond freezes solid. The more highly selected varieties such as Orandas, Ryukins, and Ranchus may survive a temperate winter in North America when left outside, but in my experience they do this with less and less success as they mature. For further discussion of temperature, see Chapter 5.

On the other hand, goldfish will not spawn naturally unless they are subjected to a seasonal temperature drop—though it doesn't have to be as cold as Ontario in January to be "winter" for goldfish. There is also evidence to suggest that the lengthening of the days in the spring also plays an important role in egg production and the onset of breeding behavior.

Filtration
Filtration is very important in goldfish keeping, primarily because goldfish are fun to feed. They can eat a prodigious amount of food if allowed, and the wastes they produce present a challenge to filtration technology. The filtration system you choose will depend upon the size of your collection and your budget, but the fundamental methods and goals of filtration are the same, whatever technology you select.

Filtration occurs on two levels. The first is mechanical, the removal of visible impurities and particles by a mechanical baffle or screen. The second level of filtration is the chemical reduction of nitrogenous waste in the water. The nitrogenous waste products come from the proteins that the fish ingest. They are released into the water in the form of ammonia, which is reduced by bacteria living on the surfaces of the filter media. We will discuss this again, in more detail, in the section on the nitrogen cycle.

A wide variety of filters are available today, including hang-on filters that are suspended from the aquarium, undergravel filters, canister filters, wet-dry filters, bead filters, sponge filters, sand filters, and even algae filters.

Filtration also creates water current and oxygenates the aquarium water. The ancestor of the goldfish is a river fish. Though they can adapt to almost any body of water as long as it is sufficiently oxygenated, goldfish tend to be more energetic and active with dynamic water current and plenty of aeration. Varieties such as Bubble Eyes and Tosakins, which are not able to move with agility because of their highly selected body shapes, cannot cope with strong water current, but most other varieties seem to enjoy it as long as there are also quieter areas in the tank where they can rest and sleep.

Ultraviolet Sterilization
Ultraviolet sterilization can be regarded as another kind of filtration. It is done by pumping water into a cylindrical chamber that contains a high-intensity ultraviolet bulb protected by a glass sleeve. The intense ultraviolet rays shine through the water, and their wavelength actually disrupts the DNA of any microorganism passing through the chamber. The ultraviolet sterilizer does not perform any mechanical or chemical filtration but can be very useful in achieving water clarity by killing suspended bacteria and algae that cloud the water. Ultraviolet sterilizers are available in varying strengths. Stronger ultraviolet sterilizers kill more pathogens, including larger pathogens such as Ichthyophthirius multi/ills ("ich," or white-spot disease).

For water clarification, including killing suspended green algae, the ultraviolet sterilizer is unsurpassed. Several manufacturers now offer small, aquarium-sized units.

With an ultraviolet sterilizer, you can achieve crystal-clear water without the use of chemicals. In addition, ultraviolet sterilizers do not harm the green algae attached to the interior of the aquarium, which helps in nitrate control.

Ultraviolet sterilizers are also helpful in caring for sick fish, because they can decrease bacterial populations in the aquarium and limit the spread of pathogens from one fish to another. I strongly recommend ultraviolet sterilization for clear, cleaner, healthier water.

Feeding
I consider feeding time the most enjoyable activity in keeping goldfish. So do many other hobbyists, which can result in overfeeding.

The number of feedings per day depends upon the age of the fish and the condition the keeper is trying to achieve. Smaller fish are in their growth phase and need many small feedings throughout the day for optimal growth and performance. Feed all they'll consume in less than five minutes several times a day.

Larger fish that are not being groomed for breeding should be fed a variety of foodstuffs once or twice per day. Feed the amount they will eat in five to seven minutes. Breeders need more frequent meals of high-protein foods, but in smaller quantities. The feeding of fry is beyond the scope of this chapter.

In spite of the fact that goldfish have been in cultivation for at least one thousand years, there is wide disagreement about what to feed them. Fortunately, they are very adaptable in their nutritional requirements, as one might expect of a species that has existed for tens of thousands of years in the wild sifting mud for tiny rotifers and crustaceans. Still, there are some facts of goldfish nutrition that all hobbyists need to be aware of.

Variety is the spice of a goldfish's life, and a fish which is fed nothing but flake food all its life will be small, badly formed, and poorly colored. It will probably also develop cataracts by the time it is five years old. Fish fed a variety of flake, pellet, and frozen foods will have the deepest bodies, most impressive body shape, and most brilliant color. They will also be the most prolific breeders.

Contrary to the advice of older works on goldfish stating that goldfish are vegetarians and need little protein, large amounts of high-quality protein are very important for growth and health. I strenuously advocate the use of a wide variety of proteins, including animal, fish, and invertebrate sources. A mixture of pellet and frozen foods is important because it is more likely to provide a full and balanced profile of amino acids, the building blocks of proteins.

Vegetable food is also important, perhaps more so in older goldfish. Many flake and pellet foods offer good-quality vegetable nutrition, and hobbyists report success with peas and other garden vegetables, prepared appropriately.

Storage of your goldfish food is critical. Refrigerate but do not freeze your fish foods. In the freezer, the fats in the foods may be "freezer burned," damaging the fat-soluble vitamins A, D, E, and K. When food is refrigerated, spoilage is reduced without the risk of the destruction of fats and their vitamin cargo.

Speaking of vitamins, a good vitamin profile in manufactured foods is important, but liquid or any other vitamins put into the water are a waste of money. The fish will not absorb them in any useful form.

Overfeeding is the most common mistake made by hobbyists. We love to watch our fish eat. There are several negative effects of overfeeding goldfish. First, the excess nitrogen can quickly exceed your filter's capacity to reduce it, and ammonia and nitrite accumulations will swiftly result, followed by sick fish. Second, the excess food in the environment can also stimulate the bloom of opportunistic bacteria. This results in cloudy water, which, again, may be followed by illness. Finally, excessive feeding can cause fish to become fat.