Ryukin

The Ryukin is a selectively bred form of goldfish with a characteristic egg-shaped, bloated body. A distinctive feature is a high dorsal "hump" that begins immediately behind the head. The dorsal fin is high and stands vertically. The caudal fin is forked, often long and flowing, with an angle between the lobes of about 90 degrees. Coloration varies from solid red, white, or black to variegated calico. Adult specimens can reach 15–20 cm in length. Sexual differences become noticeable during the spawning period: males become slimmer, and small white tubercles appear on their gill covers and pectoral fins.

The species is an artificially bred selective form and does not occur in natural conditions. The ancestors of goldfish originated from the waters of China, Korea, and Japan. In nature, their wild relatives inhabit stagnant or slow-flowing freshwater bodies with silty bottoms and abundant vegetation.

Ryukins are distinguished by their calm and peaceful disposition. They are quite active, but due to their body structure, they swim slower than many other fish. They are compatible with other peaceful species, but it is preferable to keep them in a species-specific aquarium or with other breeds of goldfish. When kept with active or aggressive tankmates, there is a risk of damage to their long fins.

A spacious aquarium of 75 liters per individual is required for keeping, as these fish create a high biological load. Powerful filtration and regular water changes are necessary. The optimal temperature is 18–22 °C, pH 6.0–8.0, and hardness 5–19 dGH. The substrate should be smooth, without sharp edges, to avoid injuries to fins and body. Plants with tough leaves are recommended, as the fish may nibble on them.

Ryukins are omnivorous and voracious. Their diet should include both animal and plant components. It is recommended to use specialized dry foods for goldfish, supplementing them with plant-based foods such as blanched lettuce or spinach. Feed in small portions several times a day, avoiding overfeeding, which often leads to digestive and swim bladder problems.

The fish are ready for breeding at about two years of age. For spawning, a separate aquarium of 50–80 liters with fine-leaved plants or special spawning substrates is used. A rise in temperature by 3–5 degrees and the addition of fresh, soft water serve as a stimulus. Typically, two to three males are placed with one female. After spawning, the parents are removed to prevent them from eating the eggs.

Ryukins are prone to diseases caused by poor water quality, overcrowding, and improper nutrition. Swim bladder disorders, fin rot, ichthyophthiriosis, and fungal infections are common. Prevention includes maintaining cleanliness, quality filtration, monitoring water parameters, and adhering to a feeding regimen. If signs of illness appear (lethargy, film, changes in body shape), isolation in a quarantine tank is required.

When choosing, pay attention to the fish's activity: a healthy individual should be active, with clean fins showing no signs of damage or film. The eyes should be clear, without cloudiness. Avoid fish with deformed spines, signs of emaciation, or an unnaturally bloated abdomen, unless it is due to overeating. It is recommended to observe the fish's behavior in the store to ensure there is no lethargy or problems with coordination.