Overview
The Ranchu Goldfish (Carassius auratus var.) is a intermediate freshwater species known for its orange-red (also calico, black) coloration. No dorsal fin. Mid to Bottom.
Origin & Appearance
Origin: Japan.
Colors: Orange-Red (also Calico, Black).
Body Shape: Deep Fusiform (oval/robust). Typical adult dimensions: 20.0 x 4.0 x 8.0.
Sexual Dimorphism: Subtle; males develop breeding tubercles in spring.
Tank & Water Requirements
| Min Tank Size | 40 gallons |
| Temperature | 59–75°F |
| pH Range | 7–8 |
| Water Hardness (GH) | 8-20 |
| Bioload | medium |
| Oxygen Demand | medium |
| Plant Safe | mostly |
| Aquarium Position | Mid to Bottom |
Behavior & Activity
Very slow clumsy waddle; no dorsal fin reduces stability; round body rolls during turns; needs calm water
Speed: 25/100Aggression: 1/10diurnalSchooling (2+)
Breeding
Moderate; egg scatterer; needs cold period
Common Diseases
💊 Ich
Expert Notes
No dorsal fin; egg-shaped body