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Goldfish : A Basic Overview

Fancy Goldfish Varieties

Fancy Goldfish Varieties

When hearing the word goldfish many will picture a small yellowish orange fish in a bowl. However, these fish come in over 120 varieties ranging from common goldfish to fancy types. Found in an array of colors, and patterns. They can grow quite large; some reaching lengths over a foot long. Goldfish are peaceful, hardy, cold water, freshwater fish descending from carps. They were first domesticated in China where they were raised for food. Today many enjoy keeping them in aquariums and ponds.  They are wonderful fish for both beginning fish keepers and long time enthusiasts.


Goldfish Bowls = Death Traps


Though the goldfish bowl bares their name this is actually a poor way to keep any fish other than the betta. Most goldfish kept in bowls will not survive very long due to several factors. Goldfish have a gluttonous apatite and will gladly consume anything edible in a tank, including baby fish. This leads to continuous growth, some types reaching lengths over 12 inches. Obviously a goldfish bowl isn’t capable of providing enough room. Their larger apatite also leads to higher amounts of waste products, such as ammonia, which can quickly pollute the water and slowly poising them. Goldfish breathe oxygen from the water. The larger the surface area the more oxygen rich the water will be. Goldfish bowls don’t have adequate openings to allow enough oxygen to enter the water.  Goldfish bowls are little torture chambers for goldfish, they will easily become stressed and most likely die.



Goldfish are the most popular aquarium fish worldwide. When given the correct nutrition and kept in a proper aquarium of the right size with accurate filtration goldfish can thrive and live long lives. Remember that goldfish can grow quite large; this is something to keep in mind when selecting a tank. A good rule of thumb is 3 gallons of water for every inch of a goldfish. If a goldfish is 4 inches long it would need a tank holding at least 12 gallons of water. If a tank has 3 goldfish, one that is 2 inches, one that is 3 inches and one that is 5 inches the tank would need to hold at least 30 gallons of water. The larger the tank the happier and healthier the goldfish will be.

Since they are quite messy a good filtration system is a must. There are many types to choose from. The 3 main categories of filtration are mechanical, biological, and chemical. Mechanical filters remove solid waste. This is achieved through circulating water so that the debris doesn’t settle on the bottom. The debris is trapped in a filter cartridge of some sort. These cartridges can be rinsed and replaced. Biological filters, bio-filters, contain a media for nitrifying, good types of bacteria, to grow. These medias can vary depending on the brand and type of bio-filters. The more oxygen the bacteria gets the more affective the bio-filter will be.  Chemical filtration is the use of chemicals to clear up impurities in the water and change the chemical makeup of the water. There are several types and brands of filters on the market, some fall strictly under one category while others may combine them.

Some may choose to add a heating system to the aquarium. Since goldfish are cold water fish a heater isn’t necessary but can be used. Goldfish are happiest in a temperature between 60 and 70 degrees.



Goldfish make excellent fish for outdoor ponds. Both common and fancy types can be kept outside; however common goldfish seem to do the best. Since they are hardy they can survive in a pond all year round if set up correctly. The pond should be deep enough so that it won’t freeze solid in winter. Different places may have different depths at which water will freeze. If there is enough oxygen in the water the fish can survive in a pond that has iced over on top.  As mentioned before the larger the surface area, the more oxygen rich the water will be.  Filtration is also important to an outside pond, goldfish are messy and one will be needed to keep the water clean. There are many brands and types on the market for outdoor ponds. Plants are great for ponds, not only are they pleasing to the eye they also provide natural filtration, and shelter for the fish. Goldfish will often nibble at the roots but pose no threat to the plants. Plants may also help with algae control, as they compete with the algae for survival.  Goldfish in ponds do not need to be fed as often as those kept in aquariums; once a day should suffice.  They will get meals throughout the day as bugs and small bits of plant matter enter the pond. A pond can be a beautiful, relaxing, peaceful and rewarding place to enjoy keeping and watching goldfish.

Illness and Disease

Goldfish, while naturally quite healthy can still become ill. Most illnesses that threaten goldfish are curable, and most can be prevented with proper care and maintenance of their environment. Here are some common illnesses found in goldfish.

Ichtyopthirius, “Ick”, is the most common disease seen in goldfish, and most other fish. Ick is a small white parasite that attaches to the fish’s body. The parasites feed of the fish’s body and will begin laying eggs and can reproduce rapidly. The onset of ick looks as if the fish has been sprinkled with salt. Ick goes through different stages and is present in the water. The onset of ick is due to poor water condition, temperature fluctuations, and overall poor care. This causes the fish to be stressed out and allows them to succumb to the parasites. Ick can be fatal if not treated. Treatment is simple; there are many anti-parasite medications on the market, many known as ick-away. Follow the instruction and the fish should recover. Ick can be prevented with proper maintenance of the tank and water condition.

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Fin Rot is yet another common illness seen in goldfish. The fins and tail look as if they are rotting and wasting away. This is noted by frayed, rotting, pale-pink-white edges on the affected area. Also blood streaks can be seen in the affected fins. This is another bacterial infection stemming from poor water conditions. It often occurs in a fish that is suffering from other issues, such as an injury. The fish is already week and stressed thus, falling prey to the infection. The infection strikes the weak fish causing the fins to rot away; sometimes this is worsened by fungus.  Fin rot can be treated with medication, either specifically for fin rot or an anti-bacteria medicine. Also clear up in problems with the water condition and add some aquarium salt for freshwater fish, this will aid in the healing process. It’s a good idea to isolate the ill fish during it’s recovery.  Like ick, fin rot can be prevented with the right maintenance of the tank and water condition.


This is also a bacterial infection that can strike week and injured fish. Poor water condition leads to fungal growth that can infect the wounds of an injured fish. The fungus will look like fluffy growth on the wounds and can be very damaging. Treatments consist of anti-fungal medications, but monitor the water condition because these medicines can damage the water quality. Also aquarium salt is helpful. Again this is caused by lack of maintenance and poor water quality, fungus will not grown in water of good quality.

Cloudy Eye

As the name implies this is the clouding over of the fish’s eye. It again is caused by poor water quality and lack of vitamins in their diet. It can also involve bacterial infections, eye flukes, and corneal damage. The eyes will appear glazed over and opaque instead of bright and clear. This makes it hard for the fish to see and may lead to decreased activity. This can be treated by improving the quality of the water, adding aquarium salt and feeding vitamin supplements.


Dropsy is an often fatal bacterial infection within the body which causes the scales to protrude from the body. Yet again this is caused by poor water quality, specifically high amounts of ammonia and nitrate. A fish that exhibits swelling of the body and has scales jutting out from the body, possible even the eyes bulging most likely has dropsy. Pop eye is a symptom that your fish may be developing dropsy. Dropsy causes the fish to retain fluid which fills the body cavity causing the scales to stick out, giving it a pinecone resemblance. Dropsy is hard to cure and is often fatal.  Treatment involves a broad based anti-bacterial medicine and the use of salt to aid the healing process.

Swim Bladder Disorder

This disorder is often a genetic problem in some varieties, most commonly seen in the egg shaped fancy goldfish.  This affects how the fish floats, they will either sink or float. Other than being a genetic disorder it can also be brought on by gas buildup within the fish’s body. This disorder makes it hard for the fish to either swim to the top of the tank or down to the bottom. To treat give the fish daphnia, which acts as a laxative to aid in the passing of gas. However, a fish with a genetic deformity will not be able to be treated. To prevent promote good water quality and soak the fish’s food before feeding. This helps prevent gas buildup.


Due to their massive appetite and their bodies’ inability to digest large amounts of food at a time, constipation is bound to happen at some point or another.  Overeating, especially high fat foods will compact in the fish’s body leading to constipation. The fish will appear bloated and will be lest active. To treat feed the fish boiled or softened peas. This will act as a mild laxative. To prevent feed the fish a balanced diet including greens and don’t overfeed proteins or fat.  



Eternal Evolution (author) from kentucky on November 12, 2010:

Thanks Brainmaster :D, I plan to wite more detailed articles about goldfish in the future. They really are great fish, very hardy. I have kept goldfish and koi for years. I have also kept other tropical fish but goldfish and koi remain my favories. When you get the fancy goldfish they are so pretty. Glad this info was helpful and good luch if you get one.

brainmaster on November 12, 2010:

I have been thinking of getting a goldfish. Great information, most first time goldfish owners don't know about. Give us more.

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