The Goldfish and Goldfish Forms

By Terry White

The humble goldfish with it's many and varied forms is without doubt the most popular and widely kept pet on the planet. It is a very hardy and versatile fish that many underestimate, it can cope with many varied conditions and habitats. They are normally the first step in fish keeping but it can take a lifetime to appreciate just how special this fish is.

Goldfish can be kept in large and small ponds, tanks, even bowls and barrels as long as the neck is big enough to allow oxygen to dissolve into the water and it is deep enough not to freeze solid in winter. In this document I shall concentrate on the most common forms for ponds; standard goldfish, comets, and shubunkins. Some of the forms of ventails, fantails, oranders and moors also do pretty well in warmish climates but can suffer from swim bladder problems and fin congestion over the winter. The more fancy forms like lionheads, celestials, and bubble eyes should really only be kept indoors, as with most animals the further it has been selectively bred from the wild form the less hardy it is.

The Goldfish (Carassius auratus) is thought to be a natural mutation of the Gibel carp (Carassius auratus gibel) sometimes called the Prussian carp it is a very close relative of the Crucian carp (Carassius carassius) and will cross breed easily with them.

It is estimated that goldfish in its wild form date back to around 1000AD but probably well predate this figure. They originated around China and were kept first as a food fish before colour mutations were noticed and they were kept as an ornamental fish. Over the centuries goldfish spread to more and more countries and by the 1600's they had been imported into Japan, another country with a long history of fish farming and cultivation. By the end of the 1600's they had reached as far as Europe and arrived in England around 1780, and the USA by 1850.

All goldfish are a dark drab olive/bronze colour when hatched which is made up of dark and red pigments. They tend to turn a red or white colour as they grow, this occurs as pigments in the skin are switched off by the fishes chromosomes. If the dark pigments are switched off the fish turns red and if the dark and red pigments are turned off the fish turns white. By selective cross breeding a higher proportion of the offspring changed colour at a predictable timescale and the bloodlines became fixed. Other natural mutations which were then developed by selective breeding include fantails and ventails. Most of these mutations are regressive (They can be bred out by crossing back to a more natural strain to increase the fishes hardiness). Later more selectively bred forms were developed and perfected but some of the more fancy forms can have problems with swim bladders, digestion and fin congestion over winter and are best kept in tanks.

Goldfish can grow to 60cm and weigh around 2.5kg but most never reach even half this size. Normal life span can be anything between 10-30+ years.

Keeping Goldfish

Goldfish are omnivorous and will eat practically anything they can fit into their mouths. They are especially fond of insect larvae and do well on pellet, stick and flake foods. They don't do too much damage to most plants, preferring to nibble rather than dig like koi.

Goldfish are prolific breeders, reaching maturity at one to two years of age. Males normally start chasing the females around mid March-April as the water temperatures rise and the days get longer but egg laying can occur right through the summer and into early autumn with the eggs attached to plants and roots. The males develop tubercles, small white pimples called a spawning rash, on the gill plates and pectoral fins that allows them to grip the female while chasing and this seems to stimulate the female to release the eggs. Normally a single female will be chased by three or four males, sometimes many more. Chasing can take place at any time of day but especially in the mornings. Most of the other fish in the pond will follow behind eating some of the eggs which can be a good thing as it is a good source of protein for them and if a high proportion the eggs hatched and survived your pond would be overrun with goldfish in a very short time as a single female can produce between a few hundred to many hundreds of thousands of eggs at a single spawning.

Ponds for goldfish should ideally be over 60cm deep (24") in the UK this will stop it getting too warm in summer or freezing solid in winter. Size depends on how many fish you would want to keep as a rule of thumb allow 1" of fish per sq ft of surface area (remember the fish will grow and reproduce) or 25cm of fish per 450ltrs of water if the pond is pumped and filtered; stick to under half that size if not.

I personally prefer not to keep goldfish in my koi pond as they do tend to fill it up when they breed so rapidly and they can be hard to catch in a large pond. I keep a separate pond of around 1000gallons, 4500ltrs, devoted to this great adaptable fish and it's many forms, where they can benefit from plant life that would be destroyed in the main koi pond.

Goldfish forms

Standard Goldfish have a short, wide head with a smallish mouth and crisp bright eyes. The body is long and flattened and arches over the back and down the belly. The fins in a healthy fish are stiff and erect. The dorsal fin rises from the middle of the back arch. The scales are bright and can be quite orange in colour with others deep shiny red. The tail (caudal fin) is moderately forked but quite short. The coloration can vary somewhat as the black bronze colour disappears and sometimes go by special names; silvery fish are called Pearls and those which turn yellow instead of red-gold are sometimes called Canaries.

The Sarassa Comet is a red and white coloured goldfish (sometimes yellow) that has a slimmer longer body and longer flowing fins than the standard goldfish. The comet was developed in the USA around the late 1880's. It is thought it was first developed by accident and later by selective breeding by the fish commission in Washington, D.C. The extensive fins and elongated body make the comet one of the most graceful swimmers of all goldfish, using smooth, darting and graceful movements.

The Shubunkin or calico is a multi-coloured goldfish that was developed by the Japanese around the beginning of the 1900's. It has a standard or comet body shape with a light blue, orange or white base colour with patterns of dark blue, black, red and white. They have few or no scales and can have different tail fin lengths; short or standard for London shubunkins and longer comet tail for Bristol shubunkins.

Fantails have a double tail fin and can be normal goldfish, sarassa, shubunkin or other form of the goldfish and are a graceful addition to the pond. Their movements are as slow and deliberate. The appearance of a fantail in a pond is a beautiful sight.

There are many other types of goldfish that can do well in ponds over summer or in warmer climates than the UK but the types above should be able to stay in the average UK pond all year round without trouble.