Here’s a comprehensive guide to choosing the right goldfish tank size, tailored to different scenarios and keeping needs:
1. Basic Size Requirements
Minimum Size: For a single adult goldfish (15–20cm in length), a tank of at least 60cm in length is recommended, with a width and height of 45–50cm.
Water Volume Calculation: The actual water volume should account for the thickness of the substrate. For example, a 60×45×45cm tank with 5cm of substrate will hold approximately 90 liters of water.
2. Recommendations for Different Scenarios
Juvenile Fish/Transition Tanks: A square or rectangular tank measuring 40cm in length, 30cm in width, and 30cm in height, with a water depth of 20–30cm.
Home Display Tanks:
Single adult fish: A 60×60×40cm square tank.
3–4 adult fish: An 80×60×50cm rectangular tank.
Varieties with well-developed fins (e.g., Thai Orandas) require a water depth of 40–50cm to support healthy fin growth.
Large Community Tanks: Tanks longer than 120cm with a width of at least 50cm, ideal for mixed goldfish breeds or aquascaping.
3. Key Considerations
Shape Selection: Prioritize square or rectangular tanks. Avoid round tanks, as they can disrupt the fish’s swimming balance.
Material Safety: Ultra-clear glass with a light transmittance of over 91% is preferred. Edges should be explosion-proof, and the base cabinet must support at least 300kg.
Filtration Matching: The filter flow rate should be 5 times the tank volume (e.g., a 60cm tank requires 300–480L/H).
4. Pitfalls to Avoid
✖ Avoid excessively high water levels (not only a feng shui concern but also harder to maintain).
✖ Don’t use undersized tanks for juvenile fish (they can restrict growth).
✖ Never overlook the actual water volume (substrate and decorations reduce effective space).
Example Setup:
An 80×50×50cm tank (approximately 150 liters after accounting for substrate) can house 5 adult goldfish, paired with a 10W filter canister and a heating system.