Bigger is better! Learn why tank size matters, how to calculate proper volume, and avoid the "inch per gallon" myth.
grundlagen · 5 Min. Lesezeit · tank size, planning, stocking, beginner
Choosing the Right Tank Size
One of the most important decisions you'll make is selecting the right tank size. Bigger is almost always better, and here's why.
The "Bigger is Easier" Principle
Contrary to popular belief, large tanks are easier to maintain than small ones:
Stable water parameters: More water = slower temperature/pH changes
Dilution of toxins: Waste is diluted in greater volume
More swimming space: Healthier, less stressed fish
Easier aquascaping: More creative freedom
Size Guidelines by Fish Type
Community Tanks
Minimum 60 liters (15 gal) for small schooling fish
100+ liters (25+ gal) for mixed community with tetras, rasboras, corys
200+ liters (50+ gal) for larger community fish (angelfish, larger barbs)
Goldfish
Single fancy goldfish: 80 liters (20 gal) minimum
Each additional fancy: +40 liters (+10 gal)
Single comet/common: 200 liters (50 gal) minimum
Pond is ideal for common goldfish
Cichlids
Dwarf cichlids (Apistos, Rams): 60+ liters
African cichlids: 200+ liters for a proper colony
Oscars, large cichlids: 300+ liters per fish
The "Inch Per Gallon" Myth
The old "1 inch of fish per gallon" rule is dangerously oversimplified!
A 30cm (12") Oscar needs 300+ liters, not 45 liters. Adult fish size, bioload, swimming behavior, and territorial needs all matter more than simple length.
Better Calculation Methods
AqAdvisor Method
Use online calculators like AqAdvisor.com that account for:
Adult fish size
Activity level
Filtration capacity
Territorial requirements
Conservative Approach
Research adult size of each species
Calculate bioload (carnivores produce more waste)
Stock to 60-70% of theoretical maximum
Leave room for growth and unexpected fry
Space vs. Budget Reality
We understand not everyone can house a 500-liter tank. Here's how to maximize smaller tanks:
For 40-60 Liter Tanks:
Nano fish only (Chili Rasboras, Ember Tetras)
Shrimp-focused tanks
Single Betta with snails
Endler's Livebearers (small group)
For 100-150 Liter Tanks:
Small community (Tetras, Rasboras, Corys)
Guppy/Platy colony
Dwarf cichlid pairs
Planted aquascapes
Tank Shape Matters
Length > Height for most fish. A long, shallow tank provides more swimming space and better oxygen exchange than a tall, narrow one.
Standard rectangle: Best for most setups
Cube tanks: Good for vertical-swimming fish (Angelfish, Discus)
Bowls: Never acceptable — poor surface area for gas exchange
Conclusion
If in doubt, go bigger. You'll never regret having extra space, but you'll often regret buying too small.
Minimum recommendation: Start with at least 60-80 liters. Your fish, your wallet (fewer problems = less medication), and your stress levels will thank you!