Goldfish are often seen as simple, low-maintenance pets, but their behavior can be surprisingly complex. If you’ve ever watched your goldfish and thought, “What are they doing?”—you’re not alone. From strange swimming patterns to unexpected interactions, goldfish display a variety of quirky habits. While some behaviors are completely normal, others could signal a problem with their health or environment. Let’s dive into eight of the weirdest goldfish behaviors and what they actually mean.

1. Gulping At The Surface

If your goldfish constantly swims to the surface and appears to be gasping for air, it might be trying to tell you something. This behavior is often a sign of low oxygen levels in the water. Goldfish need well-oxygenated water to thrive, and poor aeration or high ammonia levels can make breathing difficult. Adding an air pump, increasing water circulation, or performing a water change can help. However, if your goldfish does this occasionally, it may just be looking for food, as they quickly learn to associate the water’s surface with feeding time.

2. Swimming Erratically

Does your goldfish suddenly dart around the tank, flip upside down, or swim in circles? While this can sometimes be playful behavior, it can also indicate a problem. Erratic swimming is often caused by swim bladder disease, which affects the fish’s buoyancy. Overfeeding, constipation, or poor water quality can contribute to this condition. If your goldfish is acting frantic, check the water parameters and try feeding them cooked, peeled peas to aid digestion. If the behavior persists, a bacterial infection or parasite may be the cause.

3. Hovering At The Bottom

A goldfish that stays at the bottom of the tank for long periods might be resting, but it could also be experiencing stress or illness. Poor water conditions, high ammonia levels, or an underlying health issue may cause this behavior. If your fish is lethargic and not responding to food, it’s a red flag. Ensure your tank is clean, the water temperature is appropriate, and there are no aggressive tank mates causing stress. If the behavior continues, your goldfish might need medical attention.

4. Rubbing Against Objects (Flashing)

If your goldfish is rubbing its body against rocks, decorations, or the tank walls, it may be trying to relieve irritation. This behavior, known as “flashing,” is often a sign of parasites like ich or flukes. Check for other symptoms, such as white spots, red patches, or torn fins. If parasites are present, treating the tank with the appropriate medication and improving water quality can help. However, if no visible signs of disease are present, occasional flashing might just be a normal part of their grooming routine.

5. Chasing Other Fish

Goldfish are generally peaceful, but they sometimes chase each other around the tank. This behavior can mean different things depending on the context. If one goldfish persistently chases another, it could be a sign of mating behavior, where the male nudges the female to encourage egg-laying. However, if chasing is aggressive and leads to fin nipping, it may be a sign of dominance or stress. Ensuring enough space, hiding spots, and a balanced number of fish can help prevent bullying.

6. Changing Colors

One of the strangest things about goldfish is their ability to change color over time. If your bright orange goldfish starts turning white, black, or a different shade, don’t panic—it’s often normal. Factors like age, genetics, diet, and exposure to sunlight can influence color changes. However, sudden or extreme color shifts can indicate stress, poor water quality, or illness. If you notice rapid changes along with other concerning behaviors, test the water and ensure your goldfish is healthy.

7. Blowing Bubbles

Seeing your goldfish blow bubbles near the surface or in a corner of the tank? While it may look like they’re playing, this behavior is usually linked to oxygen levels and water conditions. Goldfish sometimes produce bubbles when they gulp air at the surface, especially if they expect food. In some cases, excessive bubble-blowing can be a sign of stress due to high ammonia or nitrate levels. A well-maintained tank with proper filtration and aeration can help keep this behavior at a normal level.

8. Lying On Its Side

A goldfish floating on its side or struggling to stay upright is often suffering from swim bladder disorder. This condition affects their ability to control buoyancy and is usually caused by overfeeding, constipation, or swallowing too much air. Feeding them fiber-rich foods like peas and ensuring they have a balanced diet can help. However, if this behavior continues, it could indicate a more serious internal issue, such as an infection. Keeping the water clean and providing high-quality food can prevent many swim-related problems.

Love Pets as Much as We Do?

Scroll up and click the ‘Follow’ button to stay updated with the latest heartwarming, hilarious, and helpful pet posts from Pawdown, delivered straight to your Microsoft Start feed and MSN homepage!