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Goldfish can live with other fish — but the list of truly compatible tankmates is shorter than most people expect. Goldfish are coldwater fish that produce heavy waste, grow large, and will eat almost anything small enough to fit in their mouths. Finding tankmates that share their temperature requirements, tolerate their water conditions, and won’t become a meal takes some planning. This guide covers what works, what doesn’t, and why.
The Ground Rules
- Coldwater only: Goldfish thrive at 65–72°F. Most tropical fish require 76–82°F. These ranges don’t overlap well — keeping tropical fish with goldfish means one group is always kept at the wrong temperature.
- Tank size matters more with tankmates: Goldfish already need large tanks. Adding tankmates increases bioload and requires additional space. Don’t add tankmates to a tank that’s already at minimum size for the goldfish.
- Goldfish will eat small fish: Any fish small enough to fit in a goldfish’s mouth is a potential meal. This rules out most nano fish and small tetras.
- Fancy and common goldfish shouldn’t be mixed: Commons outcompete fancies for food and space. Keep like with like.
Good Goldfish Tankmates
Other Goldfish (Same Type)
The most reliable goldfish tankmate is another goldfish of the same type. Fancy goldfish kept together in an appropriately sized tank coexist peacefully. Commons and comets do the same in ponds or large aquariums. Mixing fancy with common is not recommended — see our Fancy vs. Common Goldfish guide.
Weather Loach (Dojo Loach)
Weather loaches are one of the most recommended goldfish tankmates. They are coldwater fish that thrive in the same temperature range as goldfish, are peaceful bottom dwellers, and are large enough not to be eaten. They are active and entertaining, and they tolerate the water quality fluctuations that come with goldfish keeping. A group of 2–3 in a 40+ gallon tank works well.
Hillstream Loach
Hillstream loaches are coldwater fish that graze on algae and biofilm. They occupy a completely different part of the tank than goldfish and are generally ignored. They require well-oxygenated water with some flow — conditions that suit goldfish well. They are sensitive to poor water quality, so they work best in established, well-maintained tanks.
White Cloud Mountain Minnows
White cloud mountain minnows are small coldwater fish that can work with fancy goldfish in larger tanks. Adult white cloud mountain minnows are often quick enough to coexist with fancy goldfish in larger aquariums, but predation is still possible — especially as goldfish grow. Best kept in tanks of 30+ gallons with fancy goldfish only, and monitor carefully.
Nerite Snails and Mystery Snails
Snails are practical additions to goldfish tanks. They help consume algae and leftover food from the substrate and glass. Goldfish will sometimes mouth snails but rarely cause serious harm to larger snail species. Nerite snails are the most recommended — they don’t reproduce in freshwater. Mystery snails are larger and generally left alone by goldfish.
Tankmates to Avoid
Tropical Fish
The temperature mismatch is the primary problem. Keeping tropical fish at goldfish temperatures (65–72°F) causes chronic immune suppression and shortened lifespan. Keeping goldfish at tropical temperatures (76–82°F) stresses goldfish and reduces dissolved oxygen. There is no comfortable middle ground for both groups.
Small Fish (Nano Species)
Neon tetras, ember tetras, guppies, and other small fish will eventually be eaten by adult goldfish. Even if they survive initially, as goldfish grow the risk increases. Avoid any fish small enough to fit in an adult goldfish’s mouth.
Aggressive or Fin-Nipping Species
Tiger barbs and similar fin-nipping species will target goldfish fins, particularly the flowing fins of fancy varieties. Fin damage leads to fin rot and chronic stress. Avoid these species entirely.
Bettas
Bettas are tropical fish that require warmer water than goldfish. The temperature mismatch alone makes this combination unsuitable, regardless of aggression concerns.
Shrimp
Most shrimp species will be eaten by goldfish. Goldfish are opportunistic feeders and will consume shrimp of almost any size given the opportunity. Shrimp are not practical goldfish tankmates in most setups.
How to Introduce Tankmates
- Ensure the tank is large enough for both goldfish and tankmates before adding anything
- Quarantine new fish for 2–4 weeks before introducing them to the main tank
- Add tankmates when goldfish are still relatively small if possible
- Monitor feeding carefully — ensure all fish are getting adequate food
- Observe closely during the first 48–72 hours after introduction for chasing, fin damage, or feeding competition
- Have a backup plan if aggression or predation becomes a problem
See our Best Fish Tanks and Best Aquarium Filters guides for setup recommendations.