Aquarium tools · Fish & stockingUpdated October 10, 2026

Fish Compatibility Checker

Choose up to 10 species and the checker compares every pair. Each result explains why: one fish may eat the other, nip its fins, need a different temperature, or simply be too aggressive for a peaceful tank.

Who clashes with whom

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Add at least two species below. Fish that should not share a tank are joined by red lines.

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Compare up to 10 species. Your list is shared with the stocking calculator and temperature checker.

Compatibility results

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Quick answer

Fish are compatible when they share water type, temperature and pH, have similar temperaments, and neither can fit the other in its mouth or nip its fins. Neon tetras and bronze corydoras are a safe pair; adult angelfish will eat neons; tiger barbs nip bettas’ fins; and discus (28–31 °C) need water too warm for bronze corydoras (22–26 °C).

What the checker looks at

Compatibility rules and how serious each one is
Check	Result	Why it matters
Freshwater vs saltwater	Do not mix	Fish cannot survive in the other water type
No shared temperature	Do not mix	One species would always be too warm or too cold
Shared temperature under 2 °C	Caution	Very little margin; one fish lives at the edge of its range
No shared pH	Caution	Many captive-bred fish adapt, but wild fish may not
Predator 2.5× longer	Do not mix	Adults eat fish small enough to swallow
Fin nipper with long-finned fish	Do not mix	Constant nipping leads to fin damage and infection
Aggressive with peaceful	Do not mix	Bullying, injury and stress
Aggressive with semi-aggressive	Caution	May work in large tanks with plenty of cover
Territorial species at the same level	Caution	They fight over the same space

Rules use typical adult sizes and temperaments from Seriously Fish, FishBase and OATA care sheets. Individual fish vary.

Common pairings checked

Results for popular combinations
Pair	Result	Reason
Neon tetra + bronze corydoras	✓ Compatible	Peaceful, same temperature range
Guppy + platy	✓ Compatible	Peaceful livebearers with similar needs
Harlequin rasbora + honey gourami	✓ Compatible	Peaceful, both 22–28 °C
Freshwater angelfish + neon tetra	✕ Do not mix	Adult angelfish eat neons
Tiger barb + betta	✕ Do not mix	Tiger barbs nip long fins
Fancy goldfish + neon tetra	✕ Do not mix	Goldfish eat small fish and need cooler water
Discus + bronze corydoras	✕ Do not mix	No shared temperature (28–31 °C vs 22–26 °C)
Discus + sterbai corydoras	! Caution	They only share 28 °C
Dwarf gourami + betta	! Caution	Both territorial at the surface
Two male bettas	✕ Limit	One male betta per tank

How to reduce conflict in a community tank

Keep schooling fish in proper groups. Tiger barbs in groups of six or more nip each other rather than their tankmates; in small groups they turn on other fish.
Use space by level. Mix surface, mid-water and bottom fish so they do not compete for the same zone.
Break lines of sight. Plants, wood and rocks help territorial fish settle.
Add the most peaceful fish first. Territorial species added last are less likely to claim the whole tank.
Quarantine new fish. UF/IFAS advises quarantining new arrivals because white spot often comes in with them.

Frequently asked questions

Can a betta live with other fish?

Often yes, with calm, short-finned tankmates such as corydoras, small rasboras or snails, in at least 40 L. Avoid fin nippers like tiger barbs and other surface-dwelling territorial fish such as gouramis, and never keep two males together.

Can angelfish live with tetras?

Only with larger tetras. Adult angelfish reach about 15 cm and eat small tetras like neons and cardinals. Black skirt and serpae tetras nip fins, so they are not good matches either. Larger peaceful tetras such as Congo tetras (about 8.5 cm) work better.

Can goldfish live with tropical fish?

Usually not. Goldfish prefer cooler water (about 15–24 °C), produce a lot of waste and eat small fish. Most tropical fish need 24 °C or warmer.

Can freshwater and saltwater fish live together?

No. Freshwater fish cannot cope with sea salt levels and marine fish cannot survive in fresh water.

Is a caution result safe?

It means the pair can work with care: a bigger tank, more hiding places, or careful temperature control. Read the reason and decide whether you can provide that.

What to calculate next

Sources

Disclaimer: Compatibility depends on individual fish, tank size and layout. Treat these results as a guide and watch new fish closely for the first weeks. See our disclaimer.

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