Ranchu Goldfish

Carassius auratus

Animalia›Chordata›Actinopterygii

Variety of Fancy Goldfish · ranchu

📍 Japan

Considered the "king of goldfish" in Japan, the ranchu is a double-tailed fancy variety with a rounded, arched back, no dorsal fin, and a pronounced head wen that develops with age. It is more delicate than simpler goldfish varieties and requires pristine water, a low-current environment, and a spacious tank or pond; it should only be kept with other similarly disabled fancy goldfish.

Size7"

Min Tank20g

peaceful

Zonemid

Care Guide

Diet

Ranchu goldfish are omnivores requiring high-quality sinking pellets formulated for fancy goldfish, supplemented 2-3 times weekly with blanched vegetables (peas, zucchini) and occasional frozen foods like bloodworms or brine shrimp. Feed small amounts once daily, removing uneaten food within 2-3 minutes to maintain water quality.

Behavior

Ranchu are slow, methodical swimmers that spend most of their time in mid-water levels foraging along the bottom. They are peaceful and social, preferring the company of other fancy goldfish varieties, though their delicate nature and lack of dorsal fin make them vulnerable to faster, more aggressive species. They are curious and may recognize their keeper during feeding times.

Breeding

Breeding ranchu in captivity is difficult and rarely successful in home aquariums due to their specific requirements for large spawning spaces, precise temperature control, and careful pair selection. Successful breeding typically requires outdoor pond conditions or advanced aquaculture setups with careful monitoring of fry development.

Tank Mates

Fancy Goldfish

Only compatible tank mate; other fancy varieties like Ryukin and Lionhead share similar water needs and temperament

excellent

Gold Mystery Snail

Peaceful scavenger that won't compete aggressively and helps maintain water quality

good

Ramshorn Snail

Small, non-aggressive snail that aids in algae control without bothering ranchu

good

Common Diseases

Ich (Ichthyophthirius multifiliis)

Symptoms

White spots on body and fins, flashing against surfaces, rapid breathing, lethargy

Treatment

Raise temperature gradually to 28-30°C, perform 25% water changes daily, use aquarium salt (1 teaspoon per gallon) or ich-specific medication; treat for 7-10 days

Fin Rot

Symptoms

Frayed, disintegrating fins; white or black edges on fin tissue; lethargy

Treatment

Perform 50% water change immediately, improve water quality with frequent changes, treat with antibacterial medication or salt baths; remove any sharp tank decorations

Dropsy

Symptoms

Swollen belly, pinecone-like scales, lethargy, loss of appetite, difficulty swimming

Treatment

Isolate in hospital tank, perform daily 25% water changes, treat with antibiotics if bacterial; prognosis is poor; maintain pristine water conditions to prevent

Swim Bladder Disorder

Symptoms

Difficulty maintaining buoyancy, floating at surface or sinking, tilting or spinning

Treatment

Reduce feeding temporarily, offer blanched peas, maintain stable water temperature; may resolve with improved conditions; avoid overfeeding which is a common cause