Goldfish (Carassius auratus)

The oldest ornamental fish in the world. Much more demanding than you might think: they require space, filtration and cold water.

Detailed explanation

The goldfish is the ornamental fish par excellence. Bred in China for over a thousand years, selected in hundreds of forms: comet, shubunkin, oranda, ryukin, ranchu, telescope, bubble eye, lion head.

The bowl myth dies hard. A goldfish in a bowl suffers: ammonia accumulates, oxygen is scarce, space is insufficient. A goldfish needs at least 50 litres for the first specimen and 30 litres for each subsequent one. The elongated-bodied varieties (comet, shubunkin) are pond fish that can reach 30 cm.

They are cold water fish: the ideal temperature is 15-22°C. They don't need heater. Indeed, temperatures that are too high (above 25°C for prolonged periods) shorten their life and favour diseases.

Goldfish produce a lot of waste for their size. Filtration must be generous: at least 5 times the volume of the aquarium per hour of filter flow.

The diet must be varied. Specific food for goldfish (low in proteins, rich in vegetables), peeled peas (help digestion), daphnia, artemia. Don't overfeed: goldfish are greedy and will eat as long as there is food.

The varieties with short and round bodies (ranchu, oranda, ryukin) are less resistant than the varieties with elongated bodies. They have frequent swim bladder problems and swim less well. They should not be mixed with long-bodied varieties which outcompete them in competition for food.

A healthy goldfish can live 10-15 years. In the pond some reach 25 years. In a bowl it rarely exceeds 2 years.

The lesson of the goldfish is simple: no fish deserves a life in a bowl. If you don't have space for a suitable aquarium, choose a different animal.

Reference values by aquarium type

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