By Dr. Karen Shaw Becker
They're small, colorful, they live in water and children usually beg to have at least one, growing up. If you didn't have one yourself, it's probably you know someone who has. Yes, we're talking about goldfish, but the sad fact is, very few children (and many adults) are adept at keeping their graceful little water dwellers longer than a few weeks before they end up swimming over the rainbow bridge.
One of the reasons this happens so often is that parents (and the children themselves) don't understand how to maintain goldfish beyond what seems logical. A few simple facts are all that's needed to learn the basics of what these beautiful little fish need to live the long, healthy lives they're meant to. First of all, if you believe the first thing you need to purchase for your goldfish is a round, glass bowl, the average capacity being a gallon or even less, you're mistaken.
Even one single fish requires much more space than that to swim around in, and putting your fish in a tank that's too small can seriously restrict the growth potential of your goldfish, especially if there's more than one. In fact, Dr. Greg Lewbart, professor of aquatic animal medicine at North Carolina State University's College of Veterinary Medicine, maintains that a 29-gallon tank is preferred, and one that holds 20 gallons is the minimum for goldfish.1
One reason is because the smaller the bowl, the less time it takes for the water the fish lives in to become polluted. Waste, bacteria and algae are the main culprits in polluted fish tanks. Conversely, the more water there is in the tank, the less often the water needs to be changed out. It's definitely a factor that impacts your fish's longevity. I also think (with no science to prove it) that life in a tiny space is profoundly stressful, and stress is inversely related to a long lifespan.
Assembling Your 'Happy Fish' Shopping List
If you've determined that a goldfish — or a few of them — would be the perfect pet for your household, there are a few things you'll need to put on your shopping list first. After that, it's best to get these items in place before bringing your little Carassius auratus (scientific name for goldfish) home.
As one might expect, the equipment you need to set up a fish aquarium is probably not something you already have on a shelf in your garage, although a net made of fine mesh comes in handy when it's time to clean the fish tank. Scoop the goldfish up from the water very carefully and handle them as little as possible. Lewbart lists several must-have items he considers essential for an aquarium:2
A good power filter to help keep your tank clean
Substrate, such as some form of gravel that looks nice at the bottom
A thermometer to check the water temperature
A net for safely moving your fish when needed
A back-up water heater in case the power goes off
Most tap water contains chlorine, so a dechlorinating agent helps keep the ratio correct
Aquarium salt is needed to help de-stress your fish, but read the instructions before adding
A variety of top-quality fish food, like flakes and vegetable matter
The Importance of Water for Your Pet Goldfish
Regarding food and water for your goldfish, the water, of course, may be the most important. The water quality in a fish tank is probably more important than any other aspect of raising healthy, long-lived fish. Siphoning one-third of the entire tank and replacing it with fresh once per month is a good rule of thumb.
Although in the wild temperature fluctuation would be natural, too much of a swing may be dangerous. You'll need a water thermometer to check the temperature of the water occasionally so timely adjustments can be made if needed.
Goldfish are cold-blooded, so they rely on the water temperature to regulate their own. In case the power goes out, The Spruce recommends getting either a submersible heater, which is consistent and efficient, or a cable heating system, which is connected to a controlling unit and placed under the substrate.3 According to The Nest:
"Goldfish like cool water; the water temperature for their tanks should be between 65 to 68 degrees Fahrenheit. However, be careful. Typical goldfish prefer colder water, but fancy goldfish, such as black moors, veil-tails and orandas, do not. As the temperature in the tank increases, goldfish become sensitive to the limited availability of oxygen. Make sure you know the type of goldfish you have before establishing its tank's water temperature."4
There are also clip-on heaters, but those are generally designed for much smaller tanks. The best size depends on the number of gallons of water in the tank; aim for roughly between 2.5 and 5 watts per gallon of water. If you have a 25-gallon tank, that means you'll need a 75-watt aquarium heater, according to the chart provided by The Spruce.5
Fish Food — Don't Overfeed
Goldfish can live as long as 10 or 15 years if they're cared for properly, and there have been some known to live as long as 25 and 30 years. The oldest ever recorded was a crusty 43 years of age. But how they're cared for is of the utmost importance. That said, goldfish require feeding a few times every week.
As for food, always choose high-quality food for your goldfish, because you can imagine how unhealthy inferior food can be when new goldfish owners are lured in by a chance to save money. Variety is another aspect to explore, and always follow the instructions for amounts on the backs of the packaging. The Nest advises:
"Goldfish, like any pet, require proper diets. Look for high-quality flake foods and supplement them with freeze-dried foods and vegetable matter. You can even give your fish the occasional treat such as daphnia — tiny crustaceans that resemble fleas."6
In addition, do not overfeed your goldfish. Not only does it contribute to contaminated water due to excess food, there's also excess waste to consider. If someone is brought in to feed and care for your goldfish in your absence, make sure it's clear what food they should be given and how much. Pre-measured food in labeled containers works well.
A Few More Notes on Caring for Goldfish
While single goldfish are perfectly fine on their own, Lewbart advises getting four or five to start with. Keep in mind, though, that this means more water; an extra 5 gallons for each additional fish. Before you add other fish, however, quarantining is a practice that's a prerequisite for maintaining everyone's health. Infectious diseases, not to mention a deadly parasite known as ich, are a very common problem. As Vetstreet notes:
"Introduce a new, infected fish and all your current fish will likely be goners. When you bring home a new fish, put him in a separate tank for at least 30 days. If he looks good and healthy after a month, you can add him into the tank with his new friends."7
And remember, fish need proper environmental enrichment, too. Be sure to provide nontoxic items for your fish to explore — plants, rocks, structures, ceramic objects, etc., and change them regularly to provide new stimulation.
If you can no longer care for your pet, perhaps it seems like it would be humane to "relinquish" your goldfish to a nearby stream or river, but this is a terrible idea, and for several reasons. Lake Tahoe officials reported giant "mutant" goldfish measuring as long as 1.5 feet and weighing more than 4 ounces.
And in Wood Buffalo National Park in Alberta, Canada, goldfish reportedly measuring the size of dinner plates and multiplying with no end in sight have been spotted. Rather than simply dumping, one way to surrender your unwanted goldfish is by calling the pet store where they came from and asking if they'd be willing to take them back. Another alternative is to contact your regional state department of fish and wildlife.
One more thing, they say it's greener on the other side of the fence, a sentiment goldfish may agree with, because these little swimmers can also be jumpers when they're so inclined, so make sure you keep a cover on your fish tank. As Lewbart quips, "Bad things happen to good fish. They find a way to get into trouble."8
Believe it or not there are rescue organizations for fish! If you do decide to buy fish it's important to support ethical aquatic breeders, so a little homework will help you breathe easy about what pet stores or aquatic specialists you choose to do business with.