Why Does My Goldfish Swim Sideways And What To Do

Goldfish are among the most popular aquarium pets, known for their vibrant colors and peaceful demeanor. However, seeing your goldfish swimming on its side can be alarming. This abnormal behavior is not normal and typically signals an underlying health or environmental issue. While it may resemble a quirky personality trait, sideways swimming often indicates distress—most commonly related to swim bladder disorder, poor water quality, or physical injury. Understanding the root causes and knowing how to respond can mean the difference between a temporary imbalance and long-term suffering—or worse.

This guide dives deep into the reasons behind sideways swimming in goldfish, outlines practical steps to diagnose and treat the problem, and offers preventative strategies to maintain optimal fish health. Whether you're a beginner or experienced aquarist, this information will empower you to act quickly and effectively.

Understanding the Swim Bladder and Buoyancy Control

The swim bladder is a gas-filled organ that helps fish maintain neutral buoyancy—essentially allowing them to hover at different depths without sinking or floating. In goldfish, this organ is particularly sensitive due to their body shape, especially in fancy varieties like Orandas, Fantails, and Lionheads. These breeds have been selectively bred for rounder, shorter bodies, which can compress internal organs and impair swim bladder function.

When the swim bladder malfunctions, the fish loses control over its position in the water. It may float upside down, sink to the bottom, or swim erratically on its side. This condition, commonly referred to as \"swim bladder disorder,\" is not a disease in itself but a symptom of another issue—be it dietary, environmental, or infectious.

“Swim bladder issues in goldfish are often secondary to improper feeding or poor tank conditions. Addressing those factors usually resolves the imbalance.” — Dr. Alicia Nguyen, Aquatic Veterinarian

Common Causes of Sideways Swimming

Sideways swimming rarely has a single cause. Instead, it results from a combination of stressors that affect the fish’s physiology. Below are the most frequent contributors:

• Dietary problems: Overfeeding or consuming dry pellets that expand in the stomach can compress the swim bladder.
• Poor water quality: High levels of ammonia, nitrites, or nitrates stress the fish and weaken immune function.
• Sudden temperature changes: Goldfish are cold-water species, but rapid fluctuations can shock their system.
• Constipation: A common issue when fiber-rich foods are lacking, leading to bloating and pressure on internal organs.
• Physical trauma: Bumping into decorations or being attacked by tank mates can damage the swim bladder.
• Bacterial or parasitic infections: Internal infections can inflame organs and disrupt buoyancy.

Tip: Fast your goldfish for 24–48 hours if it's floating abnormally—this gives the digestive system time to clear and reduces pressure on the swim bladder.

Step-by-Step Guide to Diagnose and Treat the Issue

Addressing sideways swimming requires a systematic approach. Jumping to conclusions or using medications unnecessarily can worsen the situation. Follow these steps to identify and resolve the problem:

1. Observe the behavior closely: Note whether the fish floats, sinks, rolls, or only swims sideways during feeding. Is it eating? Are gills moving normally?
2. Test water parameters: Use a liquid test kit to check ammonia (should be 0 ppm), nitrite (0 ppm), nitrate (under 40 ppm), pH (6.5–7.5), and temperature (65–72°F).
3. Inspect diet and feeding habits: Are you feeding sinking pellets? Do the fish gulp air at the surface? Are meals spaced appropriately?
4. Check for physical signs: Look for bloating, clamped fins, bulging eyes, or frayed fins, which may indicate infection or injury.
5. Implement corrective actions: Based on findings, apply targeted treatments such as fasting, dietary adjustment, or water correction.

If Water Quality Is Poor

Perform a 30–50% water change immediately using dechlorinated water matched to the tank temperature. Clean the gravel and filter to remove accumulated waste. Re-test parameters after 24 hours.

If Diet Is the Likely Cause

Soak dry pellets in tank water for 10 minutes before feeding to prevent expansion in the gut. Introduce blanched peas (with skins removed) once or twice a week—they act as a natural laxative.

If Infection Is Suspected

Look for additional symptoms like lethargy, loss of appetite, or red streaks on the body. In such cases, isolate the fish and consider using a broad-spectrum antibiotic like kanamycin, following label instructions carefully.

Preventative Care Checklist

Prevention is far more effective than treatment when it comes to swim issues in goldfish. Use this checklist to maintain a healthy aquarium environment:

• ✅ Feed high-quality, sinking pellets designed for goldfish
• ✅ Offer blanched peas weekly to prevent constipation
• ✅ Avoid overfeeding—limit meals to what fish consume in 2 minutes, twice daily
• ✅ Maintain consistent water temperature with a reliable thermometer
• ✅ Perform weekly 25–30% water changes
• ✅ Test water parameters every 7–10 days
• ✅ Provide smooth, rounded decorations to minimize injury risk
• ✅ Ensure proper filtration with adequate flow for the tank size

Do’s and Don’ts: Managing a Goldfish with Buoyancy Issues

Do’s	Don’ts
Fast the fish for 24–48 hours to relieve digestive pressure	Feed dry flakes or pellets without soaking them first
Offer cooked, skinless peas as a natural remedy for constipation	Use human laxatives or home remedies not tested for fish
Keep the tank dimly lit to reduce stress during recovery	Place the tank in a high-traffic or noisy area
Quarantine sick fish if medication is needed	Add multiple medications at once without diagnosis
Monitor breathing rate and fin movement daily	Handle the fish unless absolutely necessary

A Real-Life Example: Bella the Oranda’s Recovery

Maria, a hobbyist from Portland, noticed her orange Oranda named Bella was swimming on her side and struggling to reach food at the bottom. The fish had been fine for months, but recently Maria upgraded the tank filter and changed the decor. She assumed the new setup was an improvement.

After reading about swim bladder issues, she tested the water and found elevated nitrite levels—likely due to the filter media being too aggressive and disrupting beneficial bacteria. She performed a 40% water change, reverted to her previous sponge filter, and fasted Bella for two days. On the third day, she fed a small portion of mashed pea.

Within 48 hours, Bella began swimming upright again. Maria now tests her water weekly and avoids sudden equipment changes. “I learned that even well-intentioned upgrades can destabilize a tank,” she said. “Now I introduce changes gradually and always monitor my fish closely.”

When to Seek Professional Help

Most cases of sideways swimming improve within a few days with proper care. However, some situations require expert intervention:

• If the fish shows no improvement after 5–7 days of dietary and water management
• If there are visible deformities, such as a curved spine or swollen abdomen
• If the fish stops eating entirely or exhibits labored breathing
• If other fish in the tank begin showing similar symptoms

In these cases, consult an aquatic veterinarian or a knowledgeable fish pathologist. Some conditions—like tumors, chronic infections, or congenital defects—may not be treatable at home. Early diagnosis increases the chances of successful recovery.

Frequently Asked Questions

Can swim bladder disorder be cured permanently?

In most cases, yes—especially when caused by diet or temporary environmental stress. However, goldfish with chronic or structural issues (such as compressed organs due to breeding) may experience recurring episodes. Lifelong management through proper feeding and tank maintenance is key.

Is it safe to use Epsom salt for a goldfish with buoyancy problems?

Yes, Epsom salt (magnesium sulfate) can help reduce swelling and aid digestion when used correctly. Use 1 tablespoon per 5 gallons of water in a quarantine tank for up to 48 hours. Do not use aquarium or sea salt as a substitute—Epsom salt is chemically different and should not be confused with sodium chloride.

Why do fancy goldfish get swim bladder problems more often than common goldfish?

Fancy goldfish have been selectively bred for compact, rounded body shapes, which can crowd internal organs and impair swim bladder function. Common goldfish and comets have more streamlined bodies, allowing better organ alignment and natural buoyancy control.

Conclusion: Act Early, Prevent Future Issues

Sideways swimming in goldfish is a warning sign—not a death sentence. With prompt attention and informed care, most fish recover fully. The key lies in identifying the root cause, whether it’s a simple case of overfeeding or a more serious water quality issue. Every adjustment you make to improve your aquarium environment benefits not just one fish, but the entire ecosystem.

Start today by testing your water, reviewing your feeding routine, and observing your fish with fresh eyes. Small changes can lead to dramatic improvements in health and longevity. Goldfish can live 10–15 years or more with proper care—don’t let a preventable issue cut their life short.

💬 Have you helped a goldfish recover from swimming sideways? Share your story in the comments—your experience could help another aquarist save their pet.