Can Bettas Live With Harlequin Rasboras?
Edited by Ivan F.
Short answer
Yes
Yes, with a full school and enough room. Harlequins are calm and quick enough to stay out of trouble, and sources often name them for a community with a betta, but expect some chasing at first.
Seriously Fish calls the harlequin very peaceful and an ideal community fish, and its Betta profile says some small cyprinids from similar environments can be suitable. One retailer says a school will stay out of a betta’s way and not dominate meals. It adds that a betta may chase them a little without much success, which it sees as harmless. If that chasing turns into cornering or torn fins, separate them.
How they compare
Figures come from our species pages. Shared ranges are where both animals are comfortable.
Betta and Harlequin Rasbora
- Adult size
- Betta: 2.8 in (7 cm)
- Harlequin Rasbora: 1.8 in (4.5 cm)
- Minimum tank
- Betta: 11 US gal (41 L)
- Harlequin Rasbora: 14 US gal (54 L)
- Temperature
- Betta: 72–86°F (22–30°C)
- Harlequin Rasbora: 70–82°F (21–28°C)
- pH
- Betta: 6–8
- Harlequin Rasbora: 5–7.5
- Hardness
- Betta: 1–15 dGH
- Harlequin Rasbora: 1–12 dGH
- Temperament
- Betta: Territorial/Aggressive
- Harlequin Rasbora: Peaceful
- Swim zone
- Betta: Top
- Harlequin Rasbora: Mid-Water
Shared by both
Temperature: 72–82°F (22–28°C)
pH: 6–7.5
Hardness: 1–12 dGH
Largest species minimum
14 US gallons (54 L), from Harlequin Rasbora. This is a starting point, not a stocking plan.
What to watch for
- Keep a real school. A small group leaves each fish easier for a betta to single out.
- Add live plants and cover, so a chased fish can get out of sight.
- Choose a tank that meets the school’s own minimum, which is larger than a betta needs alone.
- Watch for torn fins on either fish, and be ready to rehome one of them.
Tank setup
Gear for the largest setup on this page
A forgiving setup with room for a small community.
Tank size for the largest species (Harlequin Rasbora)
At least 14 US gallons (54 L)
Aqueon Standard Glass Aquarium 20 Long US
Aqueon Standard Glass Aquarium 29 Gallon US
Eheim clearTank 73 Spain
Why we chose these (Best 20-Gallon Fish Tank: 20 Long or 29?). Nobody here has used or tested them.
Filter
Hang-on-back or large sponge filter
Easy to maintain and strong enough for a community without blasting the fish.
Seachem Tidal 55 Power Filter US
Marineland Penguin PRO 175 Power Filter US
Eheim LiBERTY 130 Hang-on Filter Spain
Seachem Tidal 35 Power Filter Spain
Why we chose these (Best Filter for a 20 to 29-Gallon Tank). Nobody here has used or tested them.
Heater
Adjustable heater, about 5 W per gallon: 100 W at 20 gallons, about 150 W at 29
Enough power to hold a stable temperature in most homes. Size up for a cold room.
Aqueon Pro Adjustable Heater 100 W US
Aqueon Submersible Glass Heater 100 W US
Eheim Thermocontrol e 100 Heater Spain
Tetra HT 100 Electronic Heater Spain
Why we chose these (Best Heater for a 20 to 29-Gallon Tank). Nobody here has used or tested them.
Water Conditioner
Dechlorinator such as Seachem Prime
Tap water contains chlorine or chloramine that harms fish.
Seachem Prime US
Fritz Complete Water Conditioner US
API Betta Water Conditioner US
sera aquatan Spain
Tetra AquaSafe Spain
Sold at Kiwoko · Sold at Tiendanimal · Sold at zooplus.es · Maker's details
Why we chose these (Best Water Conditioner for Betta Fish). Nobody here has used or tested them.
Test Kit
Liquid kit such as API Freshwater Master
Tracks ammonia, nitrite, nitrate and pH while the tank cycles.
API Freshwater Master Test Kit US
API General & Carbonate Hardness Test Kit US
See it at The Shrimp Farm (a retailer; affiliate link) · Sold at Bulk Reef Supply · Maker's details
sera aqua-test box (Cl) Spain
JBL PROAQUATEST COMBISET Plus NH4 Spain
Why we chose these (Best Test Kit for a Freshwater Aquarium). Nobody here has used or tested them.
Cycle the tank before adding animals. See our guide on how to cycle a fish tank.
Frequently asked questions
Will harlequin rasboras nip a betta?
They are not known for it. Seriously Fish describes them as very peaceful. Nipping is more of a risk with fish kept in too small a group, so keep a proper school.
Do harlequins and bettas need the same water?
Their ranges overlap, and the table on this page shows where. Seriously Fish says harlequins place no special demands on water chemistry, so a betta’s tank usually suits them.