What can live with ranchu?
Other slow, round goldfish. Nothing fast, nothing tropical, nothing that nips. The ranchu is the slowest fish in the goldfish world and everything else in the tank must be too.
Good tankmates
- Other ranchu. The best option. A group of three or more is calmer and easier to feed evenly.
- Lionheads. Same shape, same speed, same needs. See how they differ.
- Orandas and pearlscales. Round-bodied and slow, though orandas can grow larger and eat faster than a small ranchu.
- Bubble-eyes and celestials, with care: they are even slower than ranchu and need a bare tank with no sharp edges.
Bad tankmates
- Comets, commons and shubunkins. Single-tailed goldfish are fast. They will eat everything before the ranchu arrives and can grow to a foot long.
- Fantails and ryukins. Faster than they look. Ryukins in particular can be pushy at feeding time.
- Tropical fish. Wrong temperature, and many (barbs, tetras, bettas) nip the wen and fins.
- Plecos and algae eaters. Common plecos are known to rasp the slime coat from slow goldfish at night.
- Snails and shrimp are safe but will be eaten if they fit in the mouth.
Numbers and space
Every fish you add needs its own 40 liters (10 gallons) and its own surface area. Overstocking is the fastest way to turn a clean tank into a nitrate problem. Run your tank through the tank calculator before adding anyone.
Quarantine every new fish for three to four weeks in a separate tub, regardless of where it came from. Flukes and ich arrive on healthy-looking fish.