Goldfish are fun pets to keep, spending much of their day swimming around all areas of the aquarium, foraging for food, and interacting with their tank mates. So, if you notice your pet sitting at the bottom of the tank, there’s clearly a problem.
There are several reasons why your fish is sitting on the bottom of the tank. The most common causes of the behaviour are poor water quality, digestive issues, and bacterial disease.
Read this guide to find out why your goldfish might be spending too much time lounging on the substrate, how to treat the problem, and what you can do to prevent it from happening again!
What does it mean when a goldfish is staying at the bottom of the tank?
Goldfish are active creatures that generally spend most of their time cruising around all parts of the water column, rooting through the substrate, searching for food scraps, and nibbling on plants.
It’s not normal behaviour for any breed of goldfish to spend all its time lying on the tank bottom.
So, what’s the problem?
Usually, the problem is due to poor water quality, some kind of digestive issue, or the side effects of a disease. That said, there are many other potential causes, and we’ll discuss them in greater detail later in this article.
Is it normal for goldfish to stay at the bottom of the tank?
No! It’s not normal for goldfish to stay at the bottom of the tank.
Although you will certainly see your fishy friend spending time in the lower area of his aquarium, he’ll be active and busy, digging in the substrate for bits of leftover food or trying to uproot your plants!
When goldfish rest or sleep, they typically do so by floating motionless in the central area of the water column. The only time I ever saw my goldfish lying on the bottom of the tank was when they were sick.
So, if your pet is resting on the tank bottom, there’s usually a problem that requires some detective work to find out what’s wrong.
Reasons why your goldfish is sitting at the bottom of the tank
To help you solve the mystery, in this part of our guide, we explain the most common reasons why your goldfish might be sitting at the bottom of the tank.
Poor water quality
In my experience, poor water quality is the most common reason for bottom-sitting in goldfish.
Goldfish are extremely messy creatures that generate a lot of waste every day. Not only do the fish spend their time constantly grazing on food scraps, algae, and plant matter, but goldfish don’t have a stomach like you and me. Instead, everything the goldfish eats passes through its digestive tract, where the nutrients in the food are extracted. The remaining waste is excreted into the water.
Suppose you don’t run a powerful, efficient filtration system and take the time to remove fish waste and general detritus once a week. In that case, the water will quickly become polluted with nitrates. Nitrates in concentration are highly toxic to all fish, even your relatively hardy goldfish, causing the fish to become lethargic, disinterested in food, and likely to crash out on the bottom of the tank.
Swim Bladder Disorder
Swim bladder disorder or disease is an extremely common problem in egg-shaped Fancy goldfish varieties. In fact, the rounder the fish’s body shape, the more prone to this condition it will be.
The fish’s swim bladder is a gas-filled organ that sits in the creature’s abdomen and controls the fish’s buoyancy. Suppose the swim bladder isn’t functioning properly. In that case, the fish will be unable to swim on an even keel, potentially tipping to one side, swimming upside down, or becoming trapped on the substrate or at the surface, unable to swim up or down.
Swim bladder disorder has several causes, including:
- Digestive problems
- Bacterial diseases
- Parasite infestation
- Malformation due to genetics
The most common cause of swim bladder problems is overeating or an incorrect diet, leading to constipation and compromising the swim bladder.
Goldfish suffering from disease or bacterial infection often become very lethargic and drift to the tank bottom, where they sit for hours without moving at all.
Look out for other telltale signs of disease, such as:
- Loss of appetite, which is highly unusual in goldfish
- Ulcers or reddened areas on the skin
- Frayed or bloody fins (fin rot)
- Fluffy white growths on the body (columnaris)
- Flashing or flicking against solid objects in the tank, followed by a rash of tiny white spots on the skin, fins, and gill covers
Some or all these signs generally indicate a bacterial infection of some kind.
Parasites can sometimes attack goldfish, either internally or externally.
Common parasites include gill flukes, anchor worms, and intestinal worms. External parasites are usually seen with the naked eye latched onto the fish’s body or gill covers. In contrast, internal parasites are undetectable until the fish shows signs of disease.
Contrary to popular myth, goldfish are highly sociable creatures that should never be kept alone. At the very least, you should have a pair of goldfish, although ideally, you want to have a large group of at least five.
If goldfish are lonely or are kept in a poor environment, they will get stressed, spend more time hiding, and might also rest on the tank bottom.
Never keep one goldfish alone in a traditional fishbowl.
Goldfish are large fish that need more swimming space than a bowl or small tank can provide.
In addition, a small tank or bowl doesn’t provide enough surface area for efficient gaseous exchange, potentially leading to oxygen deprivation, which can also harm your fish. Finally, the water quality in a goldfish bowl won’t be stable, causing temperature fluctuations and dangerous accumulations of nitrates.
Goldfish are curious fish that need lots of mental and physical stimulation to remain happy and stress-free. So, you should provide your fish with plants, rocks, pieces of driftwood, and the like that the fish can explore.
If the environment is incorrect, your fish will get stressed, leading to lethargy, failure to thrive, and bottom-sitting.
Cold water temperature
Goldfish are coldwater fish, but if the water in their tank or pond gets below 52 °F, they will become less active and won’t eat as heartily as they usually do. As the fish’s metabolism slows, they rest more and might spend time sitting on the bottom of the tank.
New tank syndrome
A common mistake that’s made by many newbies to the fishkeeping hobby is to introduce fish to the aquarium before it’s completely cycled and ready. If you do that, your goldfish will certainly sit on the bottom of the tank after just a few days.
The environment must be given sufficient time to stabilise and establish thriving colonies of healthy bacteria in the biological filter media, the substrate, and on the surfaces of decorations and plants. If that doesn’t happen, the ammonia, nitrites, and nitrates levels in the water will rapidly become extremely high, quickly making your fish sick and potentially even killing them.
So, if you’ve just set up your tank, wait for at least two weeks before adding fish. Test the water to ensure ammonia and nitrite levels are zero and nitrates are below 20 ppm. Once that’s the case, you can add a couple of fish to your new tank. Test the water daily for the next couple of weeks, and when you’re sure the conditions are right, you can add more fish.
What to do if your goldfish is sitting at the bottom of the tank
If you notice your goldfish sitting at the bottom of the tank, the first thing to do is work out why.
Test the water!
If your goldfish is lying on the substrate, breathing rapidly, and his gills appear bright red, the problem is most likely down to poor water quality and a lack of oxygen.
Start by testing the water in the tank. Ammonia and nitrite levels must be zero, and nitrates should ideally be less than 20 to 30 ppm.
If the water conditions are poor, carry out a partial water change of 30%, vacuum the substrate thoroughly to remove waste matter, clean the filter media thoroughly, and then top up the tank with dechlorinated water.
Test the water again and repeat the water change if necessary until the levels drop.
Your fish should recover within a few hours.
Look closely at your goldfish
If the water quality is not the problem, look very closely at your fish for signs of disease or parasite activity.
If you notice any of the following symptoms, it’s likely your goldfish is sick:
- Red areas on the skin
- Missing or damaged scales
- Fluffy white growths around the head and fins
- Torn or ragged fins
- White spots on the fins, body, and gill covers
- Ulcers or open sores
Lack of appetite, inactivity, and sitting on the bottom of the tank are also pretty reliable indicators that your fish is sick.
Use an antibacterial or anti parasite medication to treat your fish, placing it in a quarantine tank until it recovers. You’ll get the treatment you need from your local fish store or vet clinic.
Make dietary changes
Fancy goldfish are prone to constipation, which causes swim bladder issues, sometimes leaving the fish stranded on the bottom of the tank, unable to swim back up again.
Constipation is usually caused by overfeeding or giving the fish an exclusively dry food diet. I feed my Fancies a mixed diet of Fancy goldfish mini pellets and frozen meaty protein, such as bloodworms, daphnia, and brine shrimp. That helps to keep things moving and effectively prevents the problem.
Try offering your goldfish a small portion of a frozen meaty protein or a shelled, blanched pea. That usually fixes constipation within a matter of hours.
Check the water temperature
Goldfish are naturally much less active in extremely cold water, although they can tolerate it. Check the water temperature in your tank, and consider adding a heater if the temperature is constantly below 52°F.
Looking after your goldfish
Goldfish are generally extremely hardy creatures that will remain healthy and thrive for ten years or more if given the correct environment, diet, and good water quality.
However, if the water is dirty, the goldfish is isolated in a small tank with no mental or physical stimulation and is fed an incorrect diet; you might find it sitting at the bottom of the tank.
Fortunately, that situation is preventable. Maintain your aquarium correctly to prevent ammonia, nitrites, and nitrate levels from becoming too high, keep your fish in an enriched environment with other goldfish, and feed Fancy goldfish-specific food supplemented with frozen meaty proteins to prevent swim bladder problems.
Happy goldfish keeping!