Freshwater Fish Compatibility Chart
A freshwater fish compatibility guide showing which popular community fish get along, which combos to avoid, and the temperament, size, and water rules behind good matches.
A peaceful community tank is built, not lucky. Most fish disasters trace back to one of three mismatches: temperament, size, or water needs. Get those right and very different species coexist for years. Get them wrong and you face nipped fins, stressed hiding, or fish that simply disappear overnight. This chart shows good and bad matches for the most popular freshwater fish.
Quick answer: Match fish by temperament, adult size, and water needs, not appearance. Keep fin-nippers like tiger barbs away from bettas, angelfish, and gouramis. Never mix goldfish with tropical fish (temperature clash). House schooling fish in groups of 6+. Keep aggressive cichlids in dedicated setups. Confirm numbers fit your tank with our stocking calculator.
Community fish compatibility chart
Use this as a starting map. Individual temperament varies, tank size changes outcomes, and more space with more hiding spots almost always improves compatibility.
| Fish | Good tankmates | Avoid |
|---|---|---|
| Betta (male) | Corydoras, kuhli loaches, ember tetras, snails, shrimp (in larger tanks) | Tiger barbs, guppies, other bettas, gouramis, fin-nippers |
| Neon & cardinal tetra | Other small tetras, rasboras, corydoras, dwarf gouramis | Angelfish, large cichlids, goldfish, fin-nippers |
| Guppy, platy, molly | Each other, corydoras, snails, peaceful tetras (matched water) | Tiger barbs, bettas, large or aggressive cichlids |
| Goldfish | Other goldfish, white cloud minnows, cool-water companions | All tropical fish, bettas, small fish they can swallow |
| Angelfish | Corydoras, larger tetras (rummynose), peaceful gouramis | Neon tetras (snack-sized), tiger barbs, fin-nippers |
| Tiger barb | Own kind in groups of 6+, fast robust fish like danios | Bettas, angelfish, gouramis, any slow long-finned fish |
| Corydoras catfish | Almost all peaceful community fish, tetras, rasboras, livebearers | Aggressive cichlids, very large predatory fish |
| Dwarf gourami | Tetras, rasboras, corydoras, peaceful bottom dwellers | Tiger barbs, other gouramis (males), aggressive fish |
| African cichlids | Own lake group in dedicated hard-water cichlid tanks | Soft-water community fish, tetras, slow peaceful fish |
| Discus | Cardinal tetras, corydoras (warm-tolerant), rams, rummynose | Goldfish, cool-water fish, boisterous or aggressive species |
The three rules behind every match
Temperament comes first. Peaceful fish belong with peaceful fish, semi-aggressive with semi-aggressive, and truly aggressive species in their own tanks. The classic trap is mixing a calm, long-finned fish with a known fin-nipper. Tiger barbs in particular shred the trailing fins of bettas, angelfish, and gouramis, often before any owner notices the damage.
Size is the second rule, and it is blunt: if a fish fits in another fish's mouth, eventually it becomes a meal. Angelfish and neon tetras are a famous example, because an adult angel happily eats the same tetras that were harmless when both were small. Plan around adult sizes, not the juveniles you buy at the store.
Water needs are the third rule and the most overlooked. Two friendly fish still fail together if one needs cool water and the other warm, or one needs soft acidic water and the other hard and alkaline. Cross-check the temperature chart and the water parameters chart so every fish shares an overlapping comfort zone.
Combinations to avoid
- Bettas and fin-nippers or flashy fish: tiger barbs nip, and guppies can trigger a betta's aggression with their color and movement.
- Goldfish and tropical fish: a permanent temperature mismatch that stresses one side no matter what you set the heater to.
- Angelfish or discus with tiny fish: small tetras and shrimp become food as the larger fish mature.
- Aggressive cichlids with community fish: territorial behavior and hard-water needs make this a frequent wipeout.
- Single schooling fish: one tetra or cory is a stressed, sometimes nippy fish; always keep groups of six or more.
- Two male gouramis or two male bettas: they fight over territory in all but the largest, heavily planted tanks.
Set the tank up for peace
Tank size and aquascaping change everything. More gallons dilute aggression and give targets room to escape, while plants, driftwood, and rock caves break sight lines so territorial fish cannot patrol the whole tank. Add the boldest species last, keep schooling fish in full groups, and avoid overstocking. Plan headroom with the stocking calculator and browse individual care needs in our fish species library before you buy.
For the rest of your planning tables, including temperature, parameters, stocking, and tank sizes, visit the aquarium reference charts hub.
Frequently Asked Questions
What makes two fish incompatible?
Three things most often: temperament, size, and water needs. Aggressive or territorial fish harass or kill peaceful tankmates, large fish eat anything that fits in their mouth, and fish from very different water or temperature needs cannot both stay healthy in one tank. Fin-nippers also torment slow, long-finned fish like bettas and angelfish. Always match all three factors, not just looks, before combining species.
Can a betta live with other fish?
Often yes, in a 10 gallon or larger tank with calm, short-finned tankmates such as corydoras, kuhli loaches, ember tetras, and snails. Avoid fin-nippers like tiger barbs, brightly colored or long-finned fish that a betta may attack such as guppies, and other gouramis or a second betta. Every betta has its own temperament, so watch closely and have a backup plan if yours proves too aggressive.
Why can not goldfish live with tropical fish?
Goldfish are cool-water fish that thrive around 65 to 72 degrees, while most tropical community fish need 74 to 80. No single temperature suits both, so one group is always stressed. Goldfish are also messy, fast-growing, and large enough to eat small tetras or nip slow fish. Keep goldfish in their own setup with other goldfish or cool-water companions like white cloud minnows.
Do schooling fish really need a group?
Yes. Tetras, rasboras, danios, barbs, and corydoras are shoaling species that feel safe only in numbers, ideally six or more of the same species. Kept singly or in pairs they become stressed, hide, lose color, and sometimes turn nippy toward other fish. Buying a proper group is both a welfare requirement and a behavior fix, since a full school tends to ignore its tankmates.
Are African cichlids community fish?
Not in the usual sense. Most African cichlids are territorial, need hard alkaline water, and should be kept in species-appropriate cichlid tanks, often overstocked on purpose to spread aggression. They do not mix with soft-water community fish like tetras or with peaceful slow swimmers. If you want a cichlid community, research the specific lake group and build the whole tank around their needs.
How do I introduce new fish to reduce aggression?
Add new fish in groups rather than one at a time, rearrange the hardscape before introducing them to disrupt established territories, and add the most aggressive species last so they cannot claim the whole tank first. Quarantine newcomers for two to four weeks to avoid importing disease. Feed before introductions and keep the lights dim that evening to ease the transition.
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