Betta tank of 20-30 litres: the ideal setup, step by step
Published by Planète Pets · managing editor: Clément Lacaille · how our guides are written
The ideal betta tank holds 20 to 30 litres, with a low-flow filter, a heater set to 25-26 °C, a lid and plants reaching up to the surface. Forget the pet-shop “betta in a wine glass”: this territorial fish lives 3 to 5 years in a properly equipped tank. Full budget: 120 to 200 €.
Contents · 5 sections
Why 20 to 30 litres and not less?
Below 20 litres, temperature and pollution swing too fast for a fish that lives alone and cannot escape. Conversely, a betta rarely thrives in a very large, high-flow tank. The 25-30 litre format, 40 cm long, is the sweet spot: a bare tank costs 25-40 €, an equipped kit 60-110 €.
How do you adapt the filtration to those long fins?
The betta is a poor swimmer: strong current exhausts him and shreds his finnage. Choose a small internal filter with adjustable flow and aim the outlet at a pane of glass, or break up the flow with a plant. Our guide on choosing a filter covers flow rates; for a betta, aim for 2 times the tank volume per hour, no more.
What does the full equipment list look like?
- 25 W heater with thermostat (15 to 25 €): the betta is tropical — 25-26 °C all year round.
- An essential lid: he jumps, and he breathes humid air at the surface thanks to his labyrinth organ.
- Soft lighting 6 to 8 hours a day, included in most kits.
- Tall plants and a resting leaf: anubias, vallisneria, or a suction-cup leaf (5 to 8 €) where he sleeps near the surface.
- Fine, dark substrate (10 to 15 €) that shows off his colours.
Which decor mistakes should you avoid?
Anything that snags: sharp-edged resin ornaments and rigid plastic plants tear fins. Go for live plants and smooth driftwood, checked as in our guide to safe driftwood and rocks. Leave 2 cm of air between the water and the lid for his surface breathing.
Frequently asked questions
Can a betta have tank mates?
In 20-30 litres, stick to snails or a few adult shrimp (which he may hunt). Never another male betta, never guppies with colourful flowing tails.
Does a betta really need a heater?
Yes. At 20 °C his immune system collapses and fin rot sets in. A stable 25-26 °C is non-negotiable.
Does he need a filter if he breathes at the surface?
Yes: his labyrinth organ handles oxygen, not pollution. Without a filter, ammonia climbs just like in any other tank.
An accessory from our shop for this use: Ceramic pebble hide for shrimp and small fish (€20.90) · the whole shop
This guide is part of Planète Pets’s Fishkeeping universe. Our advice is general in nature: for any health concern, your veterinarian remains the only reference.