Betta Tank Mates: Which Species Can Share the Tank, and Which to Avoid

Aqueon is an aquarium-products maker; Aquarium Co-Op (Co-Op) and LiveAquaria (LA) are retailers; AQQA and Bubble-Magus are aquarium-equipment brands; PetMD’s care sheet is vet-written. FishBase is a scientific fish database; figures after “≈” are our conversions. All figures are for freshwater and one male betta unless stated.

Tank Size: A Betta Alone vs With Tank Mates

Source	One betta alone	Betta with tank mates
University of Illinois vet college column	“ideally” 5 gal “or larger”	Tank and filter “must increase”
Co-Op	“at least 5 to 10 gallons”	“at least 10 to 20 gallons”
Aqueon care guide	No figure	“15 gallons or larger”
Aqueon blog	“1- 5 gallons is perfect”	“size up”
LA	4 gal, kept “singularly”	“or with suitable, peaceful tank mates”
Bubble-Magus	3 and 10 gal: “one male”, no tank mates; 1 gal “far from ideal”	20 gal: “1 Betta (with tankmates, if compatible)”

Our betta tank size guide has Tree of Life’s and PetMD’s figures for one betta; our 5-gallon, 10-gallon and 20-gallon guides give betta figures.

Who Names Which Tank Mates

Source	Names	Warns against
Co-Op	Kuhli loaches, ember tetras, Malaysian trumpet snails, harlequin rasboras, corys	Prefers trumpet snails to mystery snails (below)
Aqueon care guide	“tetras, calm barbs, rasboras, live bearers, Corydoras catfish” and other “non-aggressive fish that are not overly active”	“male gouramis, fin-nippers such as tiger barbs or active fish like giant danios”
Aqueon blog	Corydoras (5+); torpedo-shaped tetras (6+, “otherwise, they may turn into little nippers”); rasboras (7+); dwarf shrimp, mystery snails, live plants	Fish “that tend to nip at others, especially those with long fins”
PetMD	“corydoras catfish, mystery snails, ghost shrimp”, some small tetras or rasboras (“size- and temperament-dependent”)	“known fin-nippers like tiger barbs, as well as long-finned species that the betta may spar with”
University of Illinois	“snails, ghost shrimp, certain species of fish, and African dwarf frogs”	Other bettas
AQQA, 20 gal	8-10 ember tetras or harlequin rasboras; pygmy corys or 6 kuhli loaches; 4-6 amano shrimp	“colorful fin-nippers like tiger barbs”
Bubble-Magus, 20 gal	8-10 tetras such as neon or rummy nose, 1-2 corys, amano or cherry shrimp	Bettas “are territorial and may not do well with tankmates”

Tree of Life, a vet clinic: “Male bettas are territorial and should be kept alone to prevent fighting” and “Avoid fin-nipping tankmates and species that may provoke aggression.” FishBase says tiger barbs are “not to be kept with long-finned fishes”.

The Named Fish: Size, Tank and Group

FishBase’s “Max length” is the largest length it lists, not a typical adult size. SL ends at “the midlateral posterior edge of the hypural plate (in fish with a hypural plate)”; TL is “the greatest length of the whole body”. LA and Co-Op do not say which length they give.

Species	Size	Tank and group, per source
Ember tetra (Hyphessobrycon amandae)	2.0 cm SL ≈0.8 in (FishBase); 1.25 in (LA); 0.8-1 in (Co-Op’s pages)	10 gal (LA). With a betta: 10 gal or larger, “at least five to six” (Co-Op). Groups: at least 6-10 (Co-Op ember guide), 6+ (Aqueon)
Harlequin rasbora (Trigonostigma heteromorpha)	5.0 cm TL ≈2.0 in (FishBase); 2 in (LA, Co-Op)	10 gal (LA). Groups: 6+ (Co-Op), 7+ (Aqueon), 8-10 (LA), 5+ (FishBase)
Neon tetra (Paracheirodon innesi)	2.5 cm SL ≈1.0 in (FishBase); 1.5 in (LA)	10 gal (LA). Groups: 6+ (LA, Aqueon), 5+ (FishBase)
Pygmy cory (Corydoras pygmaeus; FishBase: Gastrodermus pygmaeus)	2.1 cm SL ≈0.8 in (FishBase); 1 in (Co-Op)	10 gal or larger for at least 8-12 (Co-Op); “smaller aquariums” than Aqueon’s 30 gal for most corys. Corys: at least 3-6 (Co-Op betta page), 6+ (Co-Op cory guide), 5+ (Aqueon)
Kuhli loach (Pangio kuhlii)	12.0 cm TL ≈4.7 in (FishBase); 3.5 in (Co-Op); 4.5 in (LA, black kuhli)	20 gal or larger for at least 3-6 (Co-Op); 50 gal (LA, black kuhli). Groups of 6+ “if possible” (Aqueon, loaches)

FishBase’s kuhli figure is from a 1991 German aquarium atlas (its Ref. 1672). LA: “Care Level: Easy” (betta, ember, harlequin, neon) or “Moderate” (black kuhli); “Temperament: Peaceful” for all; “Diet: Carnivore” (betta, black kuhli) or “Omnivore”.

Water Ranges Beside the Betta’s

Fish ranges are FishBase’s and Aqueon’s; retailers’ differ (LA’s harlequin pH 6.0-6.5 misses Aqueon’s betta 6.8-7.5).

Species	FishBase: pH; temperature	Aqueon: pH; temperature
Betta	6.0-8.0; 24-30°C ≈75-86°F	6.8-7.5; 76-85°F
Ember tetra	pH not given; 24-28°C ≈75-82°F	Most tetras: 6.8-7.8; 75-80°F
Harlequin rasbora	5.0-7.0; 22-25°C ≈72-77°F	Most rasboras, commercially raised: 6.8-7.8; 75-80°F
Neon tetra	5.0-7.0; 20-26°C ≈68-79°F	Most tetras: 6.8-7.8; 75-80°F
Pygmy cory	6.0-8.0; 22-26°C ≈72-79°F	Most captive-bred corys: 7.0-8.0; 74-80°F
Kuhli loach	5.5-6.5; 24-30°C ≈75-86°F	Loaches: 6.0-8.0; “Temperature requirements vary depending on species”
Mystery snail (Co-Op, LA)	—	Co-Op: they “cannot live in soft water environments”; ideal “pH of at least 7.2”, 70-78°F. LA: 7.8-8.4; 68-84°F

Shrimp, Snails and Frogs

• Shrimp. Five lists above name shrimp. Co-Op’s cherry shrimp guide: “Bettas are notorious for going after shrimp.” Its rule: “if it can fit in its mouth then it’s a predator”, though “when provided with enough hiding spaces shrimp can co-exist with larger fish, but there will always be a risk.” LA, for its blue velvet shrimp, a cherry shrimp variety: “Do not house Blue Velvet Shrimp in aquariums with loaches, puffers, and other larger carnivores that will feed on invertebrates.”
• Snails. Co-Op prefers trumpet snails to “the larger mystery snail, which likes to feed during the daytime and may attract unwanted attention from your betta fish (who might mistake the snail’s long antenna for a tasty worm)”, and notes trumpet snails “are sometimes considered pests because of their prolific breeding, but if you cut back on feedings, their population will decrease.” Co-Op’s mystery snail guide has kept them with “calmer betta fish that aren’t as aggressive”.
• African dwarf frogs. The Illinois column names them. The CDC, a US federal health agency: “Children under 5, adults over 65, and people with weakened immune systems are more likely to get sick from these germs.” “Children younger than 5 years old should not handle or touch reptiles or amphibians or their environments because they are at a higher risk for serious illness and hospitalization caused by Salmonella infection.” “People can get sick from Salmonella bacteria through contact with reptiles, amphibians, or their environments, including water from their tanks or aquariums.” “Wash your hands after handling reptiles and amphibians, their food, or items in their environment.”

Disputed Fish, Source by Source

Two males: the Illinois column says bettas “should not be housed with any other betta fish because they will fight and injure each other, often resulting in death”; FishBase, “Males will fight each other.”; the AAGB, a UK fishkeeping association, “Never keep two or more adult male Bettas together as they will fight, often to the death.”; Aqueon’s blog, “Never attempt to put two male bettas into the same tank.”

Fish	One source says	Another says
Guppies	Aqueon lists “live bearers”; its livebearer guide includes “guppies”	The AAGB: “A single male Betta can be kept alone or in a suitably-sized community aquarium containing placid species that won’t attack his long fins (conversely, a male Betta may attack other fish with long fins — such as a male guppy).”
Gouramis	Co-Op has kept honey gouramis with a betta, “but it only worked out if the betta was not as aggressive so be prepared to separate them if necessary”	Aqueon: “Avoid putting them with male gouramis”
Barbs	Aqueon’s betta guide: “calm barbs”	Aqueon’s barb guide: “Some barbs communicate by nipping at each other, so avoid mixing these fish with timid, slow moving or long-finned fish such as neon tetras, angelfish, guppies or bettas.” It also names “peaceful species like cherry barbs, gold, checkerboard and pentazona barbs”.

Female Bettas and Sororities

• Male and female: the AAGB says they “should not be housed together except for breeding purposes”; FishBase: “sexes should be kept separate unless for mating”.
• Female groups: PetMD: females “may be kept in groups called a sorority, but the tank should be at least 10 gallons, and the setup needs lots of hiding places.” Tree of Life: “Females can sometimes be housed in sororities(groups) in larger, heavily planted tanks under careful monitoring.” LA: females “may be housed together with caution”.

Before Adding Tank Mates

Must-haves

The kit’s 20 gallons fit AQQA’s and Bubble-Magus’s 20-gallon betta lists (our reading). Our betta tank roundup says it has “a 100-watt heater and thermometer” per Tetra, but neither Tetra nor the listing names bettas or gives a flow figure, and they differ on the filter. A new kit is a new tank: see the cory line below and our guides to choosing fish, adding new fish and cleaning a betta tank.

What changes the list

• Your betta. Co-Op: “depending on your betta’s personality”. Its ember guide: “some bettas or dwarf gouramis can be quite territorial, so be prepared to move them if too much aggression ensues.”
• If you add honey gouramis: Co-Op: “be prepared to separate them if necessary”.
• If you add corys: Aqueon: “Pristine water quality is essential to good health in these catfish. They should never be added to new aquariums or those that have been neglected.” Co-Op: they need “a variety of sinking foods to make sure they get enough to eat.”

Frequently Asked Questions

The Illinois column: bettas “are unlikely to get lonely in their tank; however, if they are in a small tank, they may get bored.” PetMD: males are “perfectly fine kept alone, but they can also do well in a community tank with small fish.” PetMD adds: “personality varies—some bettas are chill roommates, others prefer living solo.”

AQQA, for bettas in tanks under 5 gallons: “You can add snails or shrimp as companions if space allows.” Bubble-Magus keeps 3- and 10-gallon bettas without tank mates; Co-Op asks for at least 10 to 20 gallons and Aqueon for 15 or larger.

Of the seven lists in the second table, six name corys, six a tetra and five a rasbora (our count).

Test ammonia and nitrite first, and ask an aquatic veterinarian about the fish; disease and medication are outside what this site covers.

Sources (41)

• FishBase (database), betta
• FishBase, ember tetra
• FishBase, harlequin rasbora
• FishBase, neon tetra
• FishBase, pygmy cory
• FishBase, kuhli loach
• FishBase, tiger barb
• FishBase, standard length
• FishBase, total length
• Aqueon (maker), bettas
• Aqueon, fish that live with bettas
• Aqueon, tetras
• Aqueon, rasboras
• Aqueon, Corydoras
• Aqueon, loaches
• Aqueon, barbs
• Aqueon, livebearers
• University of Illinois (vet college), bettas
• Tree of Life (vet clinic), betta care
• PetMD (vet-written), betta care sheet
• Practical Fishkeeping (magazine), AAGB guidelines
• CDC (agency), reptiles and amphibians
• Co-Op (retailer), betta tank mates
• Co-Op, betta care
• Co-Op, ember tetras
• Co-Op, cory catfish
• Co-Op, pygmy corys
• Co-Op, kuhli loaches
• Co-Op, honey gouramis
• Co-Op, cherry shrimp
• Co-Op, mystery snails
• LA (retailer), veiltail betta
• LA, ember tetra
• LA, harlequin rasbora
• LA, neon tetra
• LA, black kuhli loach
• LA, blue velvet shrimp
• LA, gold mystery snail
• AQQA (equipment brand), 20-gallon stocking
• AQQA, tanks under 5 gallons
• Bubble-Magus (equipment brand), stocking by tank size

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