Temperature18 – 22 °C
Among the many goldfish varieties, the Tosakin Goldfish stands out for its unique originality. Its main asset is a luxurious fan-shaped caudal fin, which reaches its maximum spread in the horizontal plane. Therefore, the exceptional beauty of this fish can truly be appreciated by observing it from above, rather than from the side. The body coloration of the Tosakin includes various combinations of red, orange, and silver hues; there is also a variation with a deep dark metallic color.
The Tosakin is a rare selective breed of goldfish with a short, egg-shaped body and a pointed head. Its main feature is a unique, undivided caudal fin that, when viewed from above, forms a wide fan curling forward at the edges. The fins are well-developed, and a dorsal fin is present. Coloration varies from red and orange to white, calico, and black. Adult specimens reach 15–20 cm in length.
This species is an artificially bred selective form and does not occur in the wild. The breed was created in Japan in the 19th century (Kochi Prefecture). Due to the specific structure of their body and fins, these fish are not adapted to survival in natural bodies of water.
A peaceful, slow-moving, and social fish. Due to the specific structure of their tail, Tosakins swim clumsily and slowly, making them less competitive for food compared to more active species. Species-only tanks or cohabitation only with other slow-moving goldfish breeds are recommended. These fish are prone to stress and require a calm environment.
They require a spacious aquarium with a large surface area, preferably shallow. The absence of current is important, as these fish are weak swimmers. Effective filtration is necessary to maintain high water quality, as the species is sensitive to pollution. Regular water changes are recommended. The substrate should be smooth, without sharp edges, to avoid damaging fins and eyes.
An omnivorous species. Their diet should include high-quality dry foods in the form of pellets or flakes, supplemented with vegetable components (spinach, zucchini) and frozen foods (brine shrimp, daphnia, bloodworms). Moderation in feeding is important, as these fish are prone to overeating and digestive problems.
Breeding is considered difficult and is best suited for experienced aquarists. Spawning can be in pairs or groups. To stimulate spawning, increased temperature and imitation of seasonal changes are used. Fry require careful selection (culling) to fix breed characteristics, especially tail shape. At an early age, juveniles are often kept in special containers for proper fin development.
They are most susceptible to swim bladder diseases, which is often associated with their body shape and selective breeding. Fin damage, fungal infections, and parasitic diseases can also occur with poor water quality. They are sensitive to stress and sudden changes in environmental parameters, requiring stable keeping conditions.
When purchasing, choose active, outwardly healthy specimens without signs of fin damage, ulcers, or unnatural film on the body. It is important to assess the symmetry of the tail, as this is a key breed characteristic. It is recommended to purchase fish from specialized breeders, as high-quality specimens are extremely rare in general retail.
The essentials: size, tank volume, water parameters and care
An adult reaches 15–20 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.
The recommended volume is 110 L. A smaller tank speeds up nitrate build-up and raises stress levels.
Temperature 18–22 °C, pH 6–8, hardness 5–19 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.
Around 15 years when kept properly. Lifespan depends directly on tank volume, water quality and a varied diet.
Temperament: semi-peaceful (dangerous to smaller ones). Not a predatory species, but small fish that fit in its mouth will eventually be eaten.
Recommended setup: pair (male/female). Ignoring this is a common cause of stress and disease.
Diet type: any (universal). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.
The scientific name of the species is Carassius auratus, family Cyprinids (Cyprinidae). It also appears in the literature as: Carasius auratus, Carassius buergeri, Carassius burgeri.
The water suits 196 of 208 plants in the catalogue — the easiest ones are shown first.
Afzelius's AnubiasAnacharisAnubiasBrazilian PennywortDwarf CloverDwarf CloverDwarf HygrophilaDwarf SagittariaDwarf ValGuppy GrassHornwortJava FernJava MossMoneywortMud SwordNarrow Leaf AnacharisNarrow-leaf CloverStringy MossSüsswassertangTaiwan MossTape GrassTemple PlantUssuri WatermilfoilWater Wisteria
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