Ranchu Goldfish - Carassius auratus
Ranchu Goldfish are a popular fish to own in the aquarium hobby. They are characterised by having a broad back with its tail fins that fan out almost horizontally. The Ranchu Goldfish can come in a variety of Patterns and colours. These fish can grow up to 12cm-20cm in length.
All Goldfish varieties can be traced back to the Prussian or Gibel carp. Through selective breeding of fish that developed odd genetic characteristics such as gold coloration and twin tails, all 100 plus different varieties have been created.
All Goldfish varieties have the same scientific name of Carassius auratus auratus var., not Carassius gibelio, which is interesting because no variety of Goldfish lives in the wild (unless introduced intentionally), not even the Common Goldfish.
The Ranchu Goldfish lineage can be traced back to the Maruko or Egg Fish, a fantail without a dorsal. The Egg Fish is directly linked to the twin-tailed Wakin, Japan's most popular Goldfish variety.
Key Features:
Country of Origin: Japan
Chinese Name: N/A
Japanese Name: Ranchu
Maximum size (body length): 125mm (5 inches)
Body Type: Deep and rounded, depth to be more than half the body length
Caudal Fin: Paired, divided, and forked, well spread and held above the horizontal
Dorsal Fin: Absent
Anal Fin: Paired
Scale Type: Represented in all three scale types
Eyes: Normal
Distinguishing traits: Deep-bodied, with an arched back and a wen (hood)
Special requirements: Not to be kept with single-tailed Goldfish unless a feeding regime is employed to ensure the Ranchu gets its share of the food.
Suitable Tank Size for Ranchu
Ranchu are not one of the most active varieties, so one Ranchu needs 70 liters (15 gallons UK, 18 gallons US) with a filter installed.
70 liters is a good compromise between how big the fish will grow, how big the tank is to handle, water temperature swings, and the frequency of water changes needed to keep nitrates below 30 ppm.
For each additional Goldfish, another 45 liters (10 gallons UK, 12 gallons US) are required.
If your tank is for display purposes only, get a tank slightly taller than it is wide, as taller plants such as Vallisneria can be grown, and a taller tank has a larger viewing area.
Do not place your tank where it will receive direct sunlight or strong indirect sunlight. Even strong artificial light can be a problem. Tanks produce ideal algae growing conditions with their high nitrate levels; sufficient light is all that is necessary to produce an algal bloom.
Ideal For:
The most common mistake novice Goldfish keepers make is to mix fancy varieties with single-tailed varieties. They don't realize that slow-swimming varieties such as Ranchu can't compete successfully with fast-swimming varieties for food.
What happens over time is as the single-tailed fish get the majority of the food, they get bigger and bigger, and the Ranchu doesn't thrive.
Ranchus can be kept with other Goldfish varieties, but a close watch needs to be kept on them to ensure they are thriving and getting their share of the food.
Plecos and Bristle Nose catfish used for removing algae can become a problem if they start eating the slime off the sides of your Ranchu as a protein supplement to their diet.
Any other small fish or aquatic life in the aquarium will be eaten if it can fit into your Ranchu's mouth.
Water Parameters:
- Temperature: 16-24oC (60-75oF)
- Nitrates below 30 ppm
- pH: 6.5-7.4
- GH (general hardness) of 200 ppm or above (dGH 11)
- KH (carbonate hardness) of 143 ppm or above (dKH 8)
- Water flow: Moderate to high
Feeding:
Goldfish are slow eaters compared to some fish species because they only have a rudimentary stomach. They force as much food as possible into their mouths and slowly chew and swallow it before looking for another mouthful.
During this period, dry, processed foods are dissolving. When the fish are looking for their second or third mouthful, the food has dissolved into dust that will decay and pollute the water.