How to Use the Calculator
- Enter the number of goldfish you plan to keep
- Input the average size of your goldfish (in inches). If you have a mix of sizes, use an average
- Select the growth rate that best describes your goldfish breed (e.g., Common, Oranda, Koi)
- Choose between freshwater or saltwater if applicable
- Click "Calculate" to see the recommended tank size
Understanding Goldfish Tank Requirements
Goldfish are often called "poop machines" because they produce a lot of waste. The general rule of thumb is that each goldfish needs at least 20 gallons of water, but this calculator provides a more accurate recommendation based on your specific situation.
Important Considerations
- These calculations provide the minimum tank size. Larger tanks are always better as they provide more stable water parameters
- Each goldfish should have at least 20-30 inches of swimming space
- Consider the mature size of your goldfish - some breeds can grow up to 24 inches long
- Proper filtration is essential for maintaining water quality
- Regular water changes (10-20% weekly) are necessary for healthy goldfish
Goldfish Growth Rate Guide
The growth rate selection affects the calculation because different goldfish breeds grow at different rates:
- Slow Growth (Small Tank): Breeds like Bubble Eyes or Lionheads (0.7 factor)
- Medium Growth (Standard): Common, Comet, oranda (1.0 factor)
- Fast Growth (Large Tank): Koi or large breed goldfish (1.5 factor)