Goldfish staying at the bottom: illness or just boredom?
F. MattierIt is a distressing situation that many owners face one day. You approach the glass and make this painful observation: your goldfish stays at the bottom of the tank. It is resting on the gravel, fins sometimes folded, eyes dull. Hours pass, and the observation worsens: my fish no longer moves at the bottom of the aquarium.
Immediately, worry rises. You frantically type goldfish disease on the Internet, imagine the worst, and feel guilty.
Breathe. Don’t blame yourself. Traditional fishkeeping has often taught us very bad habits. As a passionate animal advocate and biology enthusiast, I am here to guide you. A lethargic goldfish is not necessarily a doomed fish. It is a sensitive being sending you an alarm signal. Together, we will decode this silent language and discover how to restore its dignity and joy of life, thanks to the simple common sense of nature.
The symptom of withdrawal: understanding without panicking
When a goldfish rests at the bottom, it is its way of saying "stop, something is wrong in my world." It is conserving energy.
Of course, it could be a serious illness, but in the vast majority of cases, this withdrawn behavior is the direct result of exhaustion related to its environment or digestion. Your fish is not suffering from a mysterious disease that fell from the sky; it is undergoing chronic stress that we can perfectly reverse. The first step to save it is not to rush to buy chemical medicines but to question our own vision of hygiene.
The myth of "cleanliness" and the tragedy of bleach
It is one of the most common and most dramatic mistakes, yet it comes from a great intention: wanting to provide "clean" water for the animal.
The fatal mistake of the big cleaning
As soon as the fish seems weak, or as soon as the glass gets a bit covered with algae, the owner starts an extreme goldfish bowl cleaning. All the water is emptied, the gravel is scrubbed under the tap, the glass is cleaned, and sometimes, bleach is even used "to make it smell clean" and kill the supposed germs.
Healthy "dirt": the fish's shield
It is a true biological disaster. Human hygiene (which aims for sterility) is the exact opposite of aquatic hygiene. A healthy aquarium is not a sterile operating room; it is an environment teeming with beneficial bacteria invisible to the naked eye. These bacteria live in the soil, on the walls, and in the roots of plants. They transform the fish's toxic waste into harmless elements.
By emptying everything and scrubbing, you instantly destroy this vital microbiota. You plunge your goldfish into an osmotic and bacterial shock of unprecedented violence. Its environment becomes toxic within hours, exhausting it until it is pinned to the bottom. Accept that a balanced tank contains some sediment, a few algae on the bottom. This apparent "dirt" is actually your aquarium's immune system!
👉 Learn more about the notion of "clean dirt" in aquariums.
The transit problem and the famous swim bladder
If your water quality is good but your fish shows swimming or balance problems, the culprit is almost always its diet.
It is an unknown but fundamental biological fact: the goldfish has no stomach! Its esophagus is directly connected to its intestine. This particular anatomy defines its profile as a vegetarian grazer: it is made to swallow very small amounts of food continuously throughout the day.
Dry industrial food (the famous colored flakes and pellets) is therefore a biological aberration. Once swallowed, this dehydrated food soaks up water and swells massively in the fish's intestinal tract. This congestion then compresses a vital organ located right next to it: the swim bladder.
It is the small air sac that allows the fish to manage its buoyancy. Depending on how this bladder is compressed or inflated, the symptoms vary greatly: the fish may sink like a stone and remain prostrate at the bottom, or on the contrary, float involuntarily at the surface, sometimes on its side or belly up.
The solution: fasting and movement
To relieve it, the first step is to put it on a complete fast for 24 to 48 hours to purge its system. Then, forget dry flakes. Switch to live food.
Live prey, like daphnia, are naturally rich in water, fiber, and chitin. They act as a natural, gentle laxative that will unblock its transit. Above all, the jerky swimming of daphnia will awaken the predatory instinct of your lethargic goldfish, forcing it to rise from the bottom to hunt. It's an unbeatable psychological and physical medicine.
👉 Stimulate your fish's instinct with our live daphnia strains.
The vital need for greenery: the gold of duckweeds
We often forget, but the goldfish is deeply vegetarian. In the wild, it spends 80% of its time foraging and grazing on plants. A bare tank, without plants, is like an empty prison cell for it, causing deadly boredom.
It has a vital need for greenery to keep its intestines working (remember, it has no stomach!). Rather than letting it destroy expensive decorative plants, offer it a natural plant mat. Duckweeds are a delicacy it loves to nibble on (only very large individuals will attack the large duckweeds or Azolla).
By cultivating these duckweeds on the surface, you provide it with a permanent salad bowl. Even better, in an open aquarium or a poubellarium, this surface mat naturally captures small insects (flying aphids, springtails). The goldfish comes to "snatch" at the surface to catch these treats, thus recreating the virtuous circle of its natural wild behavior.
👉 Offer a natural pantry with our duckweed.
Breaking down walls: space to thrive
We need to address the uncomfortable truth, but with kindness. If your goldfish no longer moves, it may simply be because it has nowhere to go.
A goldfish is not meant to live in 20, 30, or even 50 liters. It is a powerful animal, built for swimming, that can reach 30 centimeters and live 15 years. In a small volume, it suffers from dwarfism: its body stops growing, but its internal organs continue to develop, eventually crushing each other. Its inertia at the bottom of the tank is then just the expression of deep animal depression. A goldfish needs a very large aquarium (at least 100 liters per individual) or, better yet, an outdoor pond.
Magical alternatives for small volumes
If you have a moderately sized aquarium (between 50 and 80 liters) and cannot offer anything larger, don’t despair. The solution is not to force nature but to adapt the animal to the environment.
There are incredibly hardy fish species, just as beautiful, that will live like kings in small unheated volumes without unnecessary pumping. The Medaka (Japanese rice fish) or the Tanichthys (Chinese minnow or White Cloud Mountain fish) are fantastic candidates. Lively, colorful, and perfectly suited to a natural approach both indoors and outdoors, they are a great alternative to goldfish while respecting the animal ethics we uphold.
👉Learn more about the Medaka (Japanese rice fish).
👉Learn more about the Tanichtys (the Chinese minnow or White Cloud Mountain fish).
Conclusion: restoring dignity to the fish
Seeing a goldfish lying on the sand is never a pleasant sight. But it’s a great opportunity to reflect. By stopping compulsive cleaning, offering it live food, appropriate plant cover, and ultimately the space it truly needs, you’re not just treating a symptom. You’re restoring your pet’s dignity as a fish and transforming its space into a true piece of living nature.
Mattier
FAQ: Better understand your goldfish
How can I tell if my goldfish is suffering from swim bladder issues?
The symptoms of a swim bladder problem (often due to dry food in this stomachless fish) are very recognizable. The fish loses control of its buoyancy: it may get stuck at the bottom without being able to rise easily, or conversely, float at the surface like a cork, often on its side or belly up. It desperately struggles to swim straight but always ends up unbalanced. A 48-hour fast followed by a meal of live daphnia often solves the problem.
What is the minimum aquarium size for a goldfish?
The golden rule for a common goldfish or comet is at least 100 liters per fish, within a mature and richly planted ecosystem. However, keep in mind that a goldfish is primarily a pond fish. Its true place is outdoors, in several hundred or thousands of liters of water, where nature takes its course.
Can I put floating plants if my water is heavily agitated?
It is strongly discouraged, both for the plants and your fish. Floating plants (such as duckweed, Azolla, or floating frogbit) hate turbulence and strong currents that wet the tops of their leaves and exhaust them. Furthermore, remember that the goldfish is primarily a still water fish (pond, lake), not a fast river fish! This big guy hates constantly struggling against a strong current. Reducing water agitation (or switching to a natural low-tech approach without a pump) is infinitely more beneficial for your pet’s rest and the growth of your greenery.