Best Goldfish Tank Mates

What makes a good tank mate for a goldfish?

A good goldfish tank mate lives comfortably in cool water, is too large to be swallowed, and can match the goldfish at feeding time without being nipped. The goldfish (Carassius auratus) is a domesticated member of the carp family (Cyprinidae) from East Asia, and that history shapes every criterion below.

1. Coldwater tolerance. Our goldfish range is 59–70 °F (15–21 °C). Aquarium Co-Op gives 50–70 °F and says no heater is needed, while OATA gives 59–73.4 °F as optimal for fancy goldfish. Most community fish need water warmer than that.
2. Too big to eat. fishkeeping.co.uk says goldfish eat anything that fits in their mouth, and OATA reports adults of about 25 cm in aquaria; our data uses 10 in (25.4 cm). Small fish kept with young goldfish become food as the goldfish grow.
3. Matched speed. OATA’s goldfish and fancy goldfish care sheets warn that fast single-tails such as commons and comets outcompete slow fancy goldfish for food, and OATA reports boisterous goldfish nipping the fins of slower fancies.
4. Able to live with heavy waste. Aquarium Co-Op, OATA and fishkeeping.co.uk all describe goldfish as heavy waste producers that need strong filtration and weekly water changes of 20–30%.

Aquarium Co-Op also describes goldfish as peaceful fish that do poorly with aggressive barbs and large cichlids, so the risk runs both ways. This guide belongs to our tank mates by species series, which applies the same checks to every species.

Why are other goldfish the best goldfish tank mates?

Other goldfish are the best goldfish tank mates because they share the same cool water, the same diet and the same appetite, so none of them is food for the others. fishkeeping.co.uk says goldfish are best kept with goldfish, and OATA says they can be kept alone or in groups, which is why our minimum group size is 1.

Single-tailed and fancy goldfish

The one rule within the species is to keep body types apart. Single-tailed goldfish, such as commons, comets and shubunkins, are fast swimmers. Fancy goldfish are slower, and Practical Fishkeeping says they are less hardy than single-tailed types. OATA’s two goldfish care sheets both warn that single-tails outcompete fancies for food, and OATA reports fin-nipping of the slower fish. A tank of fancies or a tank of single-tails works better than a mix.

How much room each goldfish needs

Goldfish tanks grow with every fish added. Our minimum of 48 US gal (182 L) is fishkeeping.co.uk’s figure for a first single-tailed goldfish, about 180 litres, plus 55 litres (about 12 US gallons) for each extra fish, in a tank at least 120 cm long; the same source says single-tails are better suited to a pond at full size. Fancy goldfish need less. Aquarium Co-Op gives 20 gallons for one fancy plus at least 10 gallons per extra fish, fishkeeping.co.uk gives 140 litres (37 US gallons) plus 45 litres per extra, and OATA gives 100 litres (26.4 US gallons) plus 50 litres per extra for any adult goldfish.

Which tropical fish come closest to sharing goldfish water?

A few tropical species overlap with the cool end of the goldfish range, but most of them also face a second problem. The table below lists every species in our data whose temperature range touches the goldfish range, ordered from the widest overlap to the narrowest.

Can goldfish live with zebra danios or guppies?

Neither pairing is safe, although both look possible on temperature alone. Zebra danios have the widest overlap of any fish in our data, at 65–70 °F (18–21 °C), because their own range is 65–75 °F (18–24 °C). The pairing still scores 3/10: a zebra danio grows to 2 in (5.1 cm), small enough for an adult goldfish to swallow.

Guppies score 3/10. They share only 68–70 °F (20–21 °C), at the bottom of the guppy’s range and the top of the goldfish’s, so neither species would be kept at its preferred temperature. A guppy reaches 2.4 in (6.1 cm), and its long fins match the kind of slow, finned fish OATA reports goldfish nipping. Our guide to guppy tank mates lists tropical fish that suit guppies instead.

Platies and GloFish tetras share a similar narrow band and score 3/10 and 3/10. In every case the size gap matters more over time, because goldfish keep growing long after these fish reach adult size.

Which fish should never live with goldfish?

Tropical fish that need warm water should never live with goldfish, and nor should any fish small enough to swallow. Most species in our data fail on at least one of those counts, and many on both.

Warm-water fish

Bettas, angelfish, discus, oscars, dwarf gouramis, bristlenose plecos, kuhli loaches, cardinal tetras and harlequin rasboras share no temperature range with goldfish. The betta, for example, needs 72–86 °F (22–30 °C), and discus 79–86 °F (26–30 °C). Keeping either species in goldfish water, or goldfish in theirs, means one of them lives outside its range permanently. The full reasoning for the most searched of these pairings is in the guide to bettas and goldfish compatibility, and the list of fish that live with bettas shows where the betta does belong.

Small fish

Neon tetras, cardinal tetras, Endler’s livebearers and harlequin rasboras are small enough to eat as well as needing warmer water. The Endler’s livebearer reaches only 1 in (2.5 cm) and the neon tetra 1.2 in (3 cm). fishkeeping.co.uk says goldfish eat anything that fits in their mouth, and our goldfish data notes that small fish kept with juvenile goldfish become food as the goldfish grow.

Corydoras

Corydoras score 3/10. They share only 70–70 °F (21–21 °C), and Aquarium Co-Op lists goldfish among the fish that eat corydoras. Our goldfish data adds that spiny catfish such as corydoras can lodge in a goldfish’s gills if swallowed, so the danger runs to both fish.

Do goldfish need a heater, and which other fish don't?

Goldfish do not need a heater in a room-temperature home, according to Aquarium Co-Op, the clearest statement of that kind in our data. SRAC fact sheet 7201 gives an optimum of 65–75 °F for goldfish and says they survive 32–95 °F if changes are gradual, though immunity, feeding and growth can drop outside the optimum. Tropical fish, by contrast, need water kept near 77 °F according to the Merck Veterinary Manual.

The search for fish that do not need a heater has a short answer in our data. Aquarium Co-Op says Endler’s livebearers can live unheated at room temperature, but our Endler range is 75–81 °F (24–27 °C), Seriously Fish and Practical Fishkeeping set the lower limit at 75 °F, and Endlers are small enough for a goldfish to eat. Zebra danios (65–75 °F (18–24 °C)) and amano shrimp (65–81 °F (18–27 °C)) have the coolest lower limits among the tropical species, but no source in our data says they can go without a heater. Read the aquarium temperature guide by species before leaving any tropical fish unheated, and size equipment with the guide to aquarium heaters by tank size.

Warmer is not always better for goldfish either. Practical Fishkeeping reports good growth at 72–75 °F, and fishkeeping.co.uk says fancy goldfish do better near 72 °F, both above Aquarium Co-Op’s upper figure. Our displayed range uses the overlap of Aquarium Co-Op and OATA.

Can goldfish live in a small tank with tank mates?

No. The idea that goldfish suit small starter tanks or bowls is the most common goldfish misconception, and OATA and fishkeeping.co.uk both warn that goldfish grow large enough to outgrow small tanks quickly. Our goldfish data records an adult size of 10 in (25.4 cm), a minimum tank of 48 US gal (182 L) for a single-tailed fish, and a lifespan of 6–20 years; FishBase records a maximum age of 41 years.

Adding tank mates makes the space problem worse. In our data every goldfish pairing calculates at 55 US gal (208 L) or more, because the shared figure starts from the larger minimum and rounds up to the next common tank size. A 10-gallon tank suits small tropical fish instead, and the fish for a 10-gallon community tank we recommend guide starts from species that fit. The aquarium maintenance schedule covers the weekly water changes a goldfish tank needs.

Can goldfish live with shrimp and snails?

Goldfish are a poor match for shrimp and an uncertain one for snails. Shrimp are eaten, and snails are limited by temperature.

Shrimp

Shrimp and Snail Breeder says all dwarf shrimp are on the goldfish menu, and Aquarium Co-Op lists goldfish among the fish that eat amano shrimp. Amano shrimp still score 3/10, the highest goldfish result in our data, because they are larger, at 2 in (5.1 cm), and share 65–70 °F (18–21 °C). Cherry shrimp score 3/10. The guide to cherry shrimp tank mates covers fish that leave shrimp alone.

Snails

No source in our goldfish data says whether goldfish eat snails, so the snail verdicts rest on temperature. Nerite snails need 72–79 °F (22–26 °C) and share no temperature with goldfish, and mystery snails meet the goldfish range only at 70–70 °F (21–21 °C). Our page on which fish suit aquarium snails lists better companions.

What tank size do goldfish need with tank mates?

Every goldfish pairing in our data needs at least 55 US gal (208 L), and pairings with warm-water fish such as bettas need 75 US gal (284 L) or more, though those pairings fail on temperature anyway. No goldfish tank mate fits a 5, 10 or 20-gallon tank in our data.

For goldfish-only tanks, the figures in the section on other goldfish apply: a single fancy goldfish can start at the 20 gallons Aquarium Co-Op gives, while single-tailed goldfish start at 48 US gal (182 L) and grow toward pond size. The stocking calculator checks a planned group against a tank, and the species compatibility checker scores any species not listed here against goldfish.

Plan for the adult fish from the start, because released goldfish survive. The USGS Nonindigenous Aquatic Species database (revised 2026) lists goldfish as established or reported in the wild in 49 US states, every state except Alaska, so an outgrown goldfish needs a larger tank, a pond or a new keeper, never a local waterway.