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Carassius auratus
Fancy Goldfish, Kingyo, Moor

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Carassius_auratus_2.jpg (24kb)
Adult fancy goldfish (30 cm) among wild Carassius auratus
Photo Credit: Marcos Avila

Name: Carassius auratus
Size TankpHTemp
Origin: China
20 cm 75 L 7.6 19°C


Goldfish 101

Goldfish are perhaps the longest kept "aquarium" fish in the hobby. They’ve been kept for several thousand years. With such a long history you'd think they would have morphed into this superfish that doesn't require its keeper to do anything, right? WRONG! True Golds are quite hardy and do endure much abuse, but they are still a living, breathing creature that has certain requirements that must be met in order for it to be kept as a real pet and not a discardable piece of decoration. This article should give you an idea of what are these requirements are, so you can decide if Goldfish are for you or not.

The Basics:
The biggest and often times most fatal misconception of the entire aquarium hobby is the "fish bowl". Now what fish could honestly be suited to live its life in such a ridiculously small space? Well, a Betta might handle it, but a Goldfish certainly does not. Little Goldfish who are stuffed into these things never get past their infancy, living a sad, short life. I have heard many times of owners bragging "I kept *my* goldfish alive for 6 months in its bowl", this is truly funny and sad at the same time, since these people have no idea that goldfish live to be well over 10 years in tanks of proper size, and are known to actually live 20 years or more! The reality is: Goldfish are large, messy, oxygen-hungry fish that produce a ton of waste. This is why they almost never live in that bowl for more than a few months, even if daily water changes are made.

An appropriate sized tank is needed to house goldfish. I suggest you start with a minimum of 100 liters, this size tank can house a pair of fancy goldfish quite comfortably for quite some time. Generally, a tank of greater surface area is better than one of lesser surface area, so a hexagon or pentagon type tank is not the greatest format for goldfish.

You will need a hefty bio filter as well as an extremely efficient mechanical filter to handle even a lightly populated goldfish tank. In my opinion it is best to use 2 filters, 1 dedicated to bio filtration the other dedicated to mechanical filtration. A turnover of around 10-12 times the tank volume per hour is good if you use power filters. Do keep the water level up so that too much current isn’t made, since fancy goldfish are slow moving fish that don’t have the easiest time in the world getting around anyway. You will probably find yourself replacing the mechanical media often, I have found floss to do the best job at this. I don’t personally recommend under gravel filters (UGF's) since goldfish are always digging around in the gravel and do produce some high waste loads, but a reverse flow UGF would probably do OK for complementing the biofiltration.

This really is an optional and personal preference thing, but some décor does make the fish feel safer and therefore reduces stress. Despite popular belief, fish in general don’t care if it's glow in the dark gravel and PVC pipes or a lavishly planted tank, they don’t know the difference. However, most fancy variety goldfish do have certain limitations in the décor you choose. Don’t use anything sharp that they (especially the bubble eyed types) can injure themselves on. Use small gravel, I nearly lost a goldfish due to a piece of gravel becoming stuck in its mouth. It was no simple task getting it out. Small gravel or sand is also much easier to keep clean than large gravel, as the food and waste stay closer to the top. Goldfish do like live plants, and they do benefit from the constant availability of vegetation, but they will eat most plants. So you may not want to invest in a 10 dollar a plant like a Madagascar Lace or so forth. I use Hornwort, Elodea, Java Moss, Java Ferns and Anubias Nana. They don’t eat these last three plants, but they do eat the cheap, an-inch-an-hour growing Hornwort and Elodea.

Golds in general are omnivorous, meaning that they will eat plant matter as well as animal matter. However, Golds must have some vegetation in their diet, to prevent certain digestive problems. This can be easily provided by some live plants (as mentioned above), as well as by feeding the fish chopped lettuce, chopped spinach and deshelled peas. A good quality commercial goldfish food or two should be the "staple" of the diet, with the feedings of lettuce, spinach, peas, etc, as a treat. I always skip at least 1 day of feeding per week on Goldfish as this "cleans them out" internally, which is good for them. Soak all foods prior to feeding, as this lets the food instantly sink so the fish doesn't get that big gulp of air while feeding. That can actually prevent some swim bladder problems, which they often have. Feeding lightly helps too.

Golds are difficult to sex. Although it *is* possible. The best and most accurate way, in my opinion, is the tubercules that develop on the gill plates of the mature male. They appear to be tiny white spots, you probably won't even notice them without close examination of the fish. Females also are usually a bit larger and fuller bodied. It is nearly impossible to sex a Goldfish accurately under the age of 1.5 - 2 years of age, and even after it is quite a task.

General Maintenance:
You will probably find yourself doing some hefty maintenance on a gold tank. I recommend at least a 25% weekly water change, twice weekly of 20% is much better. Your tank may even need more water changes to remain stable. You should rinse the mechanical media twice per week and change it at least every 2 weeks. Bio media should be rinsed at least every 2-3 weeks. Vacuuming the gravel at least weekly helps as well.

Typically goldfish do best in a species only tank. It is quite possible to keep other fish with them, but you must be careful with the fish that you choose. They must be placid enough, have similar water requirements and be able to handle the lower temps (18-25°C) enjoyed by goldfish. I have had mounds of success with Zebra Danios, they are relatively close relatives, and do have a lot of the same requirements as goldfish. Apple snails are marvelous algae eaters for the goldfish tank. White Clouds would probably do OK in a gold tank as well. I wouldn’t put any of the more strictly "tropical" fish like tetras, and definitely not any cichlids.

Goldfish aren’t hard to keep, provided their owners are ready to provide them what they need and aren’t afraid of a little work. They are very rewarding, personable family pets, grow large and beautiful, and live many many years.

Contributed by Lynn Smith

The ‘Common’ Goldfish Carassius_auratus_1.gif

There can be few other varieties of fish that are so frequently viewed with as much indifference and distain as the humble goldfish, Carassius auratus. Even its familiar name, the ‘Common’ Goldfish, serves to belittle its stature among those who, for one reason or another, do not wish to understand this species further. For years, probably centuries, seeing small goldfish strung up in little jars and latterly, in plastic bags, was commonplace at fairgrounds. “Throw three darts at a board,” or “Throw a hoop over a jar to win a goldfish,” the stall-holders would cry. How degrading! How many other animal species has this commonly happened to? I wonder how many goldfish lost their lives in those tiny jars and plastic bags. Indeed, how many more suffered the same fate at the hands of their new owners who, totally ignorant of their prizes’ needs, promptly tipped them into a little bowl or jar and either ‘fed them to death’ or starved them to death.

Thankfully in recent years such practises have become less commonplace and are viewed with greater importance. However, the inferior image and the stigma attached to the goldfish remain. Today the goldfish is considered by some to be a beginner’s fish, a fish to make all your mistakes on before progressing to ‘proper’ fish. The reasons for this are manifest. The Common Goldfish is easily obtained, plentiful and colourful; it does not require artificially high water temperatures when kept in temperate climates and will suffer and survive poor water conditions with greater resilience than most of its more illustrious cousins. It is, therefore, not only very cheap to purchase but, to the unenlightened, would seem to be very cheap to accommodate.

The life of the goldfish at the hands of the novice is, to say the least, something of a lottery. It is true to say that some beginners in our hobby try to do things the ‘right way’. They read books on the subject, ask questions and generally try to educate themselves in the requirements of their new pet. While they will undoubtedly make mistakes as they learn, they are at least trying to meet the fish’s most basic needs. A fish in the care of such a person stands a more than average chance, not only of a long life, but also a comfortable one.

Not all goldfish are so lucky. Some find themselves sentenced to life in a tiny, unfiltered bowl, 100 percent water changes every few days with little or no regard to the quality of the new water or as to whether it contains harmful chlorine. Or, perhaps, to the other extreme, no water changes at all. It is a miracle that any such unfortunates manage to survive this but, somehow, many seem to do so.

Opinion remains divided regarding the origin of the goldfish. There can be little doubt that it is very closely related to the crucian carp, Carassius carassius, but the question remains whether it is actually a direct descendant or just a close relative. It is certainly true that if allowed to reproduce in the wild, without the intervention of man, the goldfish will, over a few generations, revert to something very closely resembling the crucian carp. The question is, is the resulting fish the wild form of C. auratus or is it a reversion to C. carassius? According to the FBAS fish guide, booklet number 3, Dr Yoshiichi Matsui, aquatic author and Professor of Fish Culture at Kinki University in Japan, believes that the former is true and that the crucian carp is the ancestor of the goldfish. This publication also quotes Dr Otto Schindler’s opinion that while the two species are closely related, there is a dark blotch present on the caudal peduncle of the crucian carp that does not appear on the reverted form of the goldfish.

Other differences exist between the two species. The dorsal spine in the goldfish is coarsely serrated but not so in the crucian carp; the edge of the dorsal fin of the Common Goldfish is concave whereas that of the crucian carp is convex; the body of the Common Goldfish is thought by some to be more elongate than that of the crucian carp and the scale count along the lateral line is reported to be 25 to 30 in the Common Goldfish but 28 to 35 in the crucian carp, indicating a larger scale size in the Common Goldfish.

The early history of the cultivation of goldfish is equally unclear but it is generally accepted that by the time of the Sung Dynasty, around 1000 AD, goldfish were being captive bred in China. It was not, however, until around 1500 AD that goldfish first appeared in Japan and they did not find their way into Europe until the seventeenth century. The goldfish was first zoologically classified as Cyprinus auratus in 1758 in a book by Von Linné entitled Systema Naturae.

The goldfish, like all other fish, is a complex living being. Contained within the dermis, or lower skin layer of the goldfish, is a substance called guanine. This is a silvery-white colour and very reflective. It is this guanine which reflects light through the transparent scales of the fish to give it a shiny appearance. Generally, goldfish are placed in three separate groups dependent on the amount of guanine present and how it is disbursed within the fish. We know these groups as Metallic, Nacreous and Matt.

In the metallic group the guanine is placed in the upper areas of the dermis, allowing good reflection of light through the scales and giving the fish the appearance of burnished metal. Nacre means mother-of-pearl so, taking things literally, a nacreous fish has a mother-of-pearl sheen to it. This is caused by the almost complete absence of the upper layer of guanine allowing the layers situated deeper beneath the dermis to show through and giving the fish its silky lustre. A matt fish has a complete lack of guanine and, as it has no reflective tissue, a totally matt appearance all over its head and body.

The colour pigments present in any goldfish are a combination of yellow and red-orange, known as lipochromes, and black, known as melamines. In addition to these three colours there is the red colour in the blood (haemoglobin).

A metallic fish is usually a reddish orange or a deep chrome yellow. A lack of pigment will also cause some fish to be partially, or even completely silver. The olive-green colour found in reverted or ‘uncoloured’ goldfish is created by a mixture of all three pigments at various depths in the dermis.

The term ‘uncoloured’ is usually applied to metallic goldfish which do not develop the desired red-orange or yellow colouration, or even silver, but remain an olive-green colour for their entire lives. I feel this is something of a misnomer as, strictly speaking, the term ‘uncoloured’ implies a total lack of pigment and, as previously stated, a total lack of pigment leaves the white of the tissue and the reflective silver of the guanine. The nacreous fishes are by far the most colourful of the three groups. The colour pigments mix and overlap at different depths to produce a stunning range of colours including pink, red, yellow, blue, grey, black, violet and brown. The best fish have an underlying base colour of a beautiful blue created by the presence of melamines, or black pigment, deep within the adipose tissue, beneath the dermis. Interspersed over this blue is a mixture of some or all of the previously listed colours creating, in good examples, a stunning array of colour to compete with almost any other species of fish.

Matt fish are usually pink and do not have any iris to the eye, the eye is completely black. This is sometimes known as button eye or shoe-button eye. The pink colouration is caused by the haemoglobin in the blood and is particularly evident in the gill areas where the blood flow is concentrated to absorb oxygen from the gills.

The nacreous and matt versions of the Common Goldfish are known as the London Shubunkin. The standard for the London Shubunkin is identical to that of the Common Goldfish in every other way.

The next time you see a humble goldfish for sale at your local dealer’s, don’t think of it as a poor relation to your expensive tropicals at home. Consider instead the centuries of selective breeding and loving care that have gone into making it what it really is today... an attractive and challenging branch of our hobby, a real alternative for anyone looking for ‘something different’ to further their interest.

You might even start to compare individual specimens to the standard books and then, before you even realise it, you have ‘got the bug’. You may wish to try your hand at breeding goldfish, selecting the offspring that best meet the standard you are aiming for, or you could try showing your newly acquired goldfish. You will start to find out if your interpretation of the standards matches that of the judges and you will learn what to look for and what makes one goldfish a more desirable specimen than the one next to it. The next thing you will want to do is to find out about more exotic varieties of goldfish that are available, select your favourite varieties and maybe keep some of those ... but that is another subject.

Bibliography and further reading:

FBAS Booklet no. 3 - Fish Guide
FBAS Booklet no. 4 - Goldfish Standards
Fancy Goldfish Culture - F.W. Orme - Spur Publications
Goldfish Guide (3rd Edition) - Dr Y. Matsui & Dr H.R. Axelrod - TFH Publications

Contributed by Les Pearce

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