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 think they would just morph into this fish 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 survive. Now the big question “what are these requirements?” well I shall tell you in this long article.
The biggest and often times most fatal misconception of the entire aquarium hobby is the “fish bowl”. Now what fish is honestly suited to such a small space? Well a betta can handle it but certainly prefers larger quarters. Goldfish who are often stuffed into these never live very long or full happy lives. I have heard many times of owners bragging “I kept my goldfish alive for 6 months in its bowl”, this is truly funny since these fish live to be well over 10 years in even tanks of modest size. The reality is Goldfish are high oxygen fish that produce a ton of waste, this is why it cannot live in that bowl for a long time even if daily water changes are made.
An appropriate sized tank will be needed to house goldfish. I suggest you start with a minimum of 30gallons, this size tank can house a pair of fancy goldfish quite comfortably for quite some time. But a larger tank will be needed latter on as the fish mature. 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 size 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. IMO it is best to use 2 filters, 1 dedicated to bio filtration the other dedicated to mechanical filtration. A turnover of around 10-12X per hour is good. Do keep the water level up so that to much current isn’t made since fancy goldfish are slow moving fish that don’t have the easiest time in the world of 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 UGFs as goldfish are always digging around in the gravel and do produce some high waste loads, but a reverse flow UGF would probably do Ok.
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 its 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 expecially the bubble eyed types can injure themselves on. Use small gravel, I nearly lost a goldfish due to a piece of gravel becoming lodged in the 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 detris stays closer to the top. Goldfish do like live plants and they do benefit from the constant availability of vegetation, but they will eat the plants. So you may not want to invest in a 10dollar a plant Mad lace or so forth. I use hornwart, elodea, java moss(they don’t eat this), java ferns(they don’t eat this), and anubias nana(they don’t eat this either). But the do eat the cheap grow a inch a hour hornwart 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 under Décor), 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 and etc. as a treat. I always skip atleast 1 day of feeding per week on Goldfish as this “cleans them out” 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, feeding lightly helps to.
Golds are difficult to sex. Although it IS possible. The best and most accurate way IMO, is the tubercules, that develop on the gill plates of the mature male. They appear to be tiny white spots, you probably wont even notice them without close examination of the fish. Females also are usually a big larger fuller bodied. It is nearly impossible to sex a Goldfish accurately under the age of 1.5-2 years of age, even then it is quite a task.
You will probably find yourself doing some hefty maintance on a gold tank. I recommend atleast 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 atleast every 2 weeks. Bio media should be rinsed atleast every 2-3 weeks. Vacuuming the gravel atleast weekly helps as well.
Typically goldfish do best in a species only tank. Although it is quite possible to keep other fish with them. But you must be careful in the fish that you choose. They must be placid enough, have similar water conditions and be able to handle the lower temps(65-75*F) of goldfish. I have had mounds of success with Zebra Danios they are a close relative, 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 “tropical” fish like tetras and defiantly not 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 and live many years.