🧴Water care for a Goldfish: 18 to 22°C, pH 7 to 8
Goldfish : Goldfish produce a lot of waste: plan a filter turning over 4 to 5 times the tank volume per hour and a 20 to 30 percent water change every week. Monitor nitrites and nitrates with regular test kits.
🩺 The health watchpoints on this page are for information only: only a veterinarian can examine your animal and make a diagnosis.
In short: 20 to 30 cm as an adult, 100 L minimum per fish, cold water at 18 to 22 °C with no heater. Gregarious, curious and greedy, it fares poorly alone and needs companions far more than a solitary bowl. A heavy-waste cold-water fish reaching 20 to 30 cm: oversized filtration, a large volume and regular water changes are non-negotiable.
The Goldfish’s water: its real parameters
The Goldfish’s water contract has four clauses: 18 to 22°C, pH between 7 to 8, zero detectable nitrite, nitrates capped at 25 mg/L. A drop-test kit (NO2, NO3, GH, KH, pH) beats any strip — and the nitrogen cycle, three to four weeks before any fish, is non-negotiable.
Water changes and tank upkeep
10 to 20% of the volume weekly, with water near tank temperature — easy for this temperate species, gentle substrate siphoning as you go and filter media rinsed in tank water, never under the tap: chlorine sterilises your filter.
Health: what stalks the Goldfish
Known watch-points: dropsy favored by heavily loaded water and swim bladder disorders worsened by overfeeding. Nearly every aquarium disease stems from degraded water or chronic stress: test the water BEFORE treating — medicine poured into loaded water makes everything worse. Well kept, a Goldfish lives 15 to 30 years.
Frequently asked questions
What water parameters for a Goldfish?
18 to 22°C, pH 7 to 8, zero nitrites and nitrates under 25 mg/L — checked with drop tests, not by eye.
How often should a Goldfish tank get water changes?
10 to 20% weekly, water brought to temperature, filter rinsed only in tank water. Consistency beats volume.
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