Goldfish Care Guide: How to Keep Your Goldfish Happy and Healthy
Goldfish are easily one of the most mistreated and abused fish in the hobby. These fish are won at carnivals, end up in bowls, and typically wind up living a very short and miserable life. To make matters worse, a comet, an oranda, and a bubble eye might all technically be goldfish, but their setups and care requirements are very, very, very different. So, in today's video, we're going over what actually matters when it comes to keeping your goldfish happy and healthy.
But first, a quick history lesson. Goldfish belong to the carp family and were domesticated centuries ago from their wild counterpart. Through generations and generations of selective breeding, they were developed for specific colors, body shapes, fin types, size, and eyes. And understanding that history is so important because when you drastically alter a fish's anatomy, you completely change how it swims, how it digests food, and what kind of environment it actually needs to survive.
The Main Types of Goldfish
Single tail. These are going to be your commons, your comets, and your shubunkins. These are your classic larger and more streamlined goldfish. Now, the good about them, they have a natural body structure. They're fast, powerful, gorgeous swimmers, and biologically, they are extremely hardy. The reality check: that hardiness gives people the false impression that they're going to be a great beginner fish, but they are absolutely terrible beginner fish. These fish can grow to be about a foot long. So, they are going to need a lot, a lot, a lot of space. These fish actually require at least 75 gallons for one fish. But realistically, these fish belong in something like a stock tank or a full-on pond.
Standard fancy goldfish. These are going to be your fantails, orandas, ryukins, and ranchus, and black moors. These fish are slower, rounder, and much more practical for your indoor aquarium. Their compressed egg-shaped body directly leads to swimming struggles, though: slower digestion, and can lead to swim bladder and buoyancy issues. These fish typically need a 30-gallon tank for the first fish, plus an additional 10 gallons for every additional fish. But you want to remember that the tank's footprint actually matters a lot more than the tank's height.
Smaller or dwarf fancies. Certain compact fancies or slower growing varieties fall into a slightly different tier. You can realistically get away with around a 20-gallon tank for a single smaller fancy. Just always keep in mind that smaller does not mean this is a nano fish. Even with a 20-gallon tank, you'll still need strong biological filtration and good surface area. So when I say a 20-gallon tank, I mean like a 20-gallon long or a 20-gallon breeder, not a 20-gallon tall. That is not going to help us if we are keeping goldfish.
Extreme fancy goldfish. These are going to be your bubble eyes, your celestial eyes, and your pearl scales. Just because they're shorter in length does not mean that they are easier to care for. They are the opposite of that. Bubble eyes, for instance, can easily, easily damage or tear their eyes. These fish are going to need extremely gentle flowing water, smooth substrate, and absolutely zero sharp decorations in your tank, and they can only go in with peaceful tankmates that won't out compete them for food.
Goldfish Myths, Debunked
Goldfish only grow to the size of their tank. This is probably the biggest myth in the entire hobby. People think that a small tank keeps the fish from growing huge, but what actually happens is horrifying. Goldfish release a growth inhibiting hormone. In a large body of water like a pond that gets diluted enough that it won't cause a problem. But in a small tank or bowl, those hormones will build up and stunt the fish's outer growth. These fish wind up deformed, miserable, and sometimes unable to even swim.
Goldfish are easy, beginner friendly fish. Goldfish are cold water carp with no true stomach. Food goes in, barely gets processed, and comes right out as waste. When it comes to bioload, keeping goldfish is like keeping a cold water Oscar. You are going to be dealing with massive bioload, which means you need serious filtration and water volume.
My fish lived for 3 years in a bowl and it was totally fine. This is my most hated one. Goldfish can be extremely hardy, which means that they can slowly survive in toxic water for years before dying. But surviving is not the same thing as thriving. A fancy goldfish should live about 10 to 15 years, and a single tail can easily hit 20 to 30 years in a pond.
What Actually Matters for Your Setup
Surface area. For goldfish, it's all about surface area. Tank shape matters so much more than how many gallons you have. Atmospheric gas exchange only happens right at the water surface where the water meets the air. So a tall 40-gallon tank and a 40-gallon breeder might hold the same water volume, but a 40-gallon breeder gives you massive surface area for oxygen transfer and wide horizontal swimming room. Deep narrow tanks just trap that stagnant oxygen poor water at the bottom, which doesn't help your fish.
Oxygen, temperature, and bubblers. Goldfish require a lot of oxygen, and warmer water physically holds less dissolved oxygen than cold water. During your summer heat waves, dissolved oxygen plummets, right as your fish's demand for more oxygen increases.
Substrate. Should you go bare bottom or sand or gravel? Goldfish spend a lot of their time sifting at the bottom. Standard pea gravel is the exact size to get wedged in their mouth or throats, which can lead to a terrifying moment with tweezers trying to save a choking fish. Fine sand can be great if you're going for a natural look. They can safely sift the sand through their gills, and waste sits on the top instead of rotting underneath. Then we have the bare bottom tanks. This is a fan favorite for pure simplicity. It might not look like a natural riverbed, but maintenance is unbeatable. Waste has nowhere to hide and you can siphon it clean in 2 minutes flat, and you will be siphoning a lot. So, anything that makes it easier is probably a good move.
Filtration and flow. You want a heavy turnover with a fair amount of biological media. So, canisters, oversized hang on the back filters, or sump systems work really well for goldfish. Running a large sponge filter alongside your main filter can add huge biological surface area and reliable aeration. Now, when it comes to managing current, this is really important because slower fancies can get exhausted if they are blown around their tank. So, you want to aim your spray bars at the glass or add a baffle to the outflow, so that you get great surface agitation without turning your tank into a hurricane.
Tank mates. Goldfish setups typically work best as a species-only tank. You don't want to mix fast single tails with slow fancies, as the comets can and will steal all the food every single time. I would skip tropical community fish, as they often have way different needs for their temperature and often get eaten. Always remember, if it fits in a fish's mouth, it's food.
Plants. Now, goldfish will try to eat just about any plant that you put in there. But since plants are incredible nitrate sponges, here's how you can often make that work. We all know I'm going to say it. Duckweed. I know duckweed can be a love-hate relationship, but treat it like a self-replicating salad bar. It sucks up nitrates, and goldfish love grazing on it. You can also pick tougher plants like anubias and java fern. These have thick leaves that typically taste bitter to goldfish. So you can just tie them to a rock or piece of driftwood, but remember not to bury their rhizome in the substrate. Then we have one of my favorite hacks: sticking house plant roots like pothos or peace lilies right into the top of your tank or filter. The leaves stay safe above the water while the bare roots suck up massive, massive amounts of nitrates below.
Water parameters and diet. The ideal temperature is going to be between 65 and 72 degrees Fahrenheit. And they prefer neutral to slightly alkaline water with moderate hardness. But you don't want to chase perfection with a ton of pH altering chemicals because stability is what is best for these fish. And of course, ammonia and nitrites always need to be at zero. As for diet, goldfish can struggle sometimes with floating flakes, because gulping air at the surface can trigger buoyancy issues. So, you'll want to feed high quality sinking pellets or gel foods, and fiber like blanched peas or zucchini. And please always pre-soak the pellets so that they don't expand inside their digestive tract.
Common Issues to Watch For
Buoyancy issues. Floating upside down or struggling to swim down is usually caused by swallowing too much air, constipation, or it could be a genetic issue. And these usually respond well to fasting or adding more fiber.
Bloat. This is going to be physical gut swelling from food impaction, which also typically responds well to fasting and adding more fiber.
Dropsy. If you see scales sticking straight out like a pine cone, this is often due to fluid buildup and organ failure. Dropsy is a serious, serious medical issue and unfortunately usually the fish does not make it.
Maintenance
Now when it comes to maintenance, there is no one-size-fits-all schedule. A heavily planted tank, a pond, a bare bottom 40-gallon breeder, all process waste differently. So you'll want to remember that clear water does not mean clean water. If you see your nitrates climbing, that lets you know that you need larger water changes, possibly less food, lighter stocking, or more plant roots.
So, you'll want to choose your setup based on the specific type of goldfish that you plan to keep. Give them plenty of floor space, lots of surface agitation, proper filtration, and high fiber sinking foods, and let the water test numbers guide your routine.
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