Beginner's Guide to Goldfish Keeping

Goldfish are the most beloved ornamental fish in Japan's history. Many people start with goldfish scooping at festivals and develop it into a serious hobby. However, "goldfish are hardy so they can be kept carelessly" is a misconception—providing proper conditions is the secret to long-term keeping. This guide covers all the basics beginners need to know.

Choosing a Tank

Goldfish are surprisingly large fish. Common goldfish (Wakin type) adults can reach nearly 30cm. Long-term keeping in small bowls is difficult, so use these guidelines:

• For 1-2 goldfish: 45-60cm tank (approximately 30-60 liters)
• For 3-5 goldfish: 60-90cm tank (approximately 60-160 liters)

More water volume means more stable quality and less stress. The image of "goldfish can live in small containers" is outdated. Tank-based keeping with filtration is best for goldfish health.

Choosing a Filter

Goldfish produce a lot of waste, making water dirty quickly. Filtration is especially important.

• Hang-on filter: For smaller tanks. Easy to install and beginner-friendly
• Top filter: Best for 60cm+ tanks. High filtration capacity, commonly used for goldfish
• Canister filter: Quiet with high capacity, but slightly complex to install

For goldfish, choose a filter rated for a slightly larger tank than yours.

Water Preparation Basics

Tap water cannot be used directly. Prepare water as follows:

1. Add dechlorinator to tap water per instructions
2. Match the temperature to the goldfish tank (within ±2°C)
3. Pay special attention to temperature differences during seasons requiring heaters or water changes

Goldfish are relatively cold-tolerant, with an optimal range of 15-25°C. In summer, use cooling fans or aquarium chillers to prevent exceeding 30°C.

Feeding

Goldfish eat eagerly when they see food, but overfeeding is strictly prohibited.

• Frequency: Twice daily
• Amount: What can be consumed in 2-3 minutes (remove any remaining)
• Types: Goldfish-specific flakes, pellets, and frozen bloodworms in balance

Uneaten food causes water quality deterioration. Goldfish have lower digestive capacity than other fish, so reduce food or stabilize temperature with a heater in winter when digestive problems are more likely.

Water Change Rules

Regular water changes are the most important maintenance for goldfish longevity.

• Frequency: 1-2 times per week
• Amount: 1/3 to 1/2 of total volume
• Procedure: Add dechlorinated water matched to tank temperature

Use a gravel vacuum during changes to remove substrate debris (waste, uneaten food). Complete water changes are never recommended—they destroy beneficial bacteria and crash the tank.

Common Goldfish Keeping Mistakes

• Overcrowding: Ensure at least 10-20 liters per fish
• No heater (indoors): Sudden temperature changes cause health problems
• Skipping water changes: Goldfish produce heavy waste, so neglect causes rapid deterioration

Our Goldfish Variety Guide covers popular varieties like Wakin, Ryukin, and Ranchu in detail. On Bri-Choku, you can purchase show-quality goldfish directly from breeders. Care advice is also available directly from breeders, so take advantage of this resource.