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Ranchu Goldfish

Ranchu Goldfish

Posted by Max Gandara on on 28th May 2025

Ranchu Goldfish: The Majestic Lion of the Fancy Goldfish World

Often called the “King of Goldfish” in Japan, the Ranchu Goldfish is a beloved ornamental fish known for its round, egg-shaped body, lack of a dorsal fin, and pronounced head growth, or wen. This beautiful, slow-swimming goldfish is a favorite among aquarists and collectors for its graceful swimming style and gentle temperament.

What is a Ranchu Goldfish?

The Ranchu is a fancy goldfish variety that originated in China and was perfected in Japan. It is characterized by:

  • A smooth, curved back with no dorsal fin, giving it a unique silhouette.

  • A rounded body and tucked-in tail, resulting in a waddling, elegant swimming motion.

  • A distinct, bumpy head growth (wen) that develops more as the fish matures.

  • Available in a wide range of colors, including red, white, calico, orange, black, and even metallic or matte finishes.

Ranchus are often judged in competitions for their symmetry, head growth, and back curve rather than color alone.

Why Choose a Ranchu?

  • Elegant and Unique Appearance: Their body shape and head growth give them a regal, sculpted look.

  • Slow and Peaceful: Perfect for calm aquariums without fast or aggressive tankmates.

  • Interactive and Curious: Ranchus often recognize their keepers and beg for food.

  • Living Art: Considered ornamental fish for collectors and hobbyists alike.

Tank Setup and Care

  • Tank Size: Minimum 20 gallons for one Ranchu, plus 10–15 gallons per additional fish.

  • Water Temperature: 65–75°F (18–24°C); avoid sharp fluctuations.

  • pH: 6.5–7.5

  • Filtration: Gentle filtration is key to avoid strong currents, which can stress these slow swimmers. Use sponge filters or adjustable-flow filters.

  • Substrate & Decor: Smooth gravel or bare bottom is ideal. Add gentle plants and rounded decorations to prevent injury.

  • Lighting: Moderate lighting enhances their coloration but avoid overly bright conditions.

Feeding Ranchu Goldfish

  • Diet: Omnivorous. Feed high-quality sinking pellets formulated for goldfish to avoid air gulping.

  • Supplement with blanched veggies (zucchini, spinach, peas) and occasional protein-rich treats like bloodworms or brine shrimp.

  • Feeding Frequency: 2–3 times daily in small portions to avoid bloating and swim bladder issues.

Behavior and Tankmates

  • Temperament: Extremely peaceful. Ranchus are slow and deliberate, making them ideal for goldfish-only tanks.

  • Tankmates: Best housed with other fancy goldfish of similar size and swimming ability (e.g., Oranda, Ryukin, Lionhead). Avoid fast or aggressive fish that will outcompete them for food.

Special Considerations

  • Swim Bladder Sensitivity: Due to their body shape, Ranchus are prone to buoyancy issues. Feeding sinking foods and avoiding floating pellets helps.

  • Head Growth Care: Keep water clean to prevent infections in the wen. Some breeders trim the wen if it obstructs vision, but this is best left to experts.

  • Temperature Stability: Sensitive to rapid changes—use a heater in colder climates to maintain stability.

Final Thoughts

The Ranchu Goldfish is a refined, slow-moving beauty that brings grace, character, and artistic value to any aquarium. With their unique look and calm demeanor, they are a joy for both beginner and advanced aquarists willing to provide the gentle care they deserve.

Interested in keeping Ranchu Goldfish? Set up a peaceful tank with good water quality, feed them a nutritious diet, and enjoy one of the most admired goldfish varieties in the world.