All species
fishbeginner
Goldfish
Carassius auratus
A hardy coldwater fish that grows huge and lives decades — a 20+ gallon tank with strong filtration, never a bowl.
6–12 in10–20+ years
Habitat
Enclosure
20 gal for the first fish, +10 gal for each additional
Temperature
65–72°F coldwater
Humidity / Water
Freshwater · pH 7.0–7.4
Heating & lighting
No heater — goldfish prefer cool, oxygen-rich water. Double the filtration you think you need; they're heavy waste producers.
Diet
Feed these
- Sinking goldfish pellets
- Blanched deshelled peas
- Frozen bloodworms
- Blanched zucchini
Never feed
- Floating flakes as the only food (air gulping)
- Bread
- Overfeeding
- Tropical fish food long-term
Feed what they finish in 30 seconds, twice a day. Sinking food prevents swim-bladder issues from gulping air at the surface.
Cohabitation
Can live with
Other goldfish — same type and size White Cloud Mountain minnows
Never house with
Betta — needs warmer water Neon tetras — temperature mismatch Guppies — temperature mismatch Angelfish — temperature mismatch & predation risk
Only with other cool-water fish of similar size. Tropical tank mates either overheat the goldfish or the goldfish eats them.
