While goldfish are certainly one of the most hardy fish, it is important to educate yourself about these fascinating species before you actually go out and buy additions for your tank.
In terms of longevity, goldfish have been known to live as long as 25 years and some have been noted to grow as long as two feet in length. Goldfish are frequently thought of as being inexpensive; however, collectors will pay up to $1,000 and even more for a prized specimen from the goldfish family.
There are actually more than 125 varieties of goldfish; ranging from the common pet shop goldfish to the fancier species of goldfish. Some goldfish, particularly the bulging eyed varieties, can appear to be quite deformed; however, they are highly prized by goldfish enthusiasts and breeders.
The comet is the most common goldfish. This is the variety with the pointy tail. The shubunkin; which is blue and speckled, is perhaps the most widely known of the straight-tailed varieties. Both of these types of goldfish are fairly robust and easy to maintain. In addition, both varieties will grow fairly large when provided with adequate space and care.
Fancy goldfish, most of which have round bodies and long flowing fins as well as other interesting aspects, usually reach smaller adult sizes. These also tend to be far less robust and are more sensitive. In addition, the fancy varieties tend to suffer from illness more frequently; particularly bacterial infections. This can be avoided if you keep the water in good condition; however, that requires additional vigilance and maintenance.
While common goldfish and fancy goldfish can be kept together it is really best to keep them separately. This is because the straight-tailed varieties tend to be faster swimmers and are more boisterous while the fancy varieties are not as good swimmers. As a result, the fancy varieties may be bullied by the straight-tailed varieties.
It is best to purchase your goldfish from a store that really knows their fish and avoid department stores who likely have little knowledge about the fish they sell. Avoid fish with dorsal fins that are not erect, as this can be a sign the fish is sick. Fish that appear to have to work at getting to the bottom of the tank should also be avoided, as should fish which appear to be much smaller than fish of the same age.
If you are buying fancy goldfish with bulging or bubble eyes, avoid those with eyes that are either too small or too large. Bubbles which are too small may not grow enough and those that are too big may grow so large that it makes it difficult for the fish to swim later.
Be sure to check out all of the fish in the tank and be very skeptical about buying any fish which are in the same tank with a fish that appears to be sick. If there is a fish in the tank that seems sickly, the others may as well be sick too.
It is important to keep in mind when buying a goldfish that while they are hardy even the common varieties of goldfish require good care to ensure their survival. This includes providing them with a sufficient sized tank. Goldfish are often associated with bowls but in reality they should be provided with enough space to allow them to grow. Depending on variety, they can grow from six to fourteen inches and can live, on average, from seven to ten years.
To provide an adequate home to two goldfish, your tank should be at least twenty gallons. While this can seem large, goldfish grow quickly to fill the space. The water should be de-chlorinated and a good filtration system made available. Provided the temperature of the water remains between 65 and 75 degrees, you will not need a heater. In addition, you will not need gravel on the bottom of the tank; but if it is used, you should make sure it is siphoned regularly to remove fish waste and excess food.
Avoid overfeeding your new goldfish. Remember the rule; never feed more than your fish can eat in five minutes twice per day. This will help to keep your fish happy and your water cleaner.