What do ranchu eat?
Sinking food, small amounts, two or three times a day. The staple matters less than the fact that it sinks.
The staple
A sinking pellet or a gel food with 35 to 45% protein. Sinking is the point: ranchu that feed at the surface gulp air, and their compact bodies cannot handle it. Soak dry pellets for a minute so they do not swell inside the fish. Brands aimed at fancy goldfish and ranchu (Japanese and Thai keepers have several) are fine; a good general goldfish sinking pellet is also fine. Avoid flakes altogether.
For growth and color
- Frozen bloodworm two to three times a week. Rinse first.
- Frozen or live brine shrimp and daphnia. Daphnia also acts as a laxative.
- Color foods with astaxanthin or spirulina deepen red; they will not add red to a white fish.
- Green water and algae. Fish in a lightly green tub graze all day, which is one reason outdoor fish grow better.
Fiber
Once or twice a week: blanched, skinned peas, blanched spinach or lettuce, duckweed or a slice of cucumber. Fiber keeps the gut moving, and a moving gut is the difference between a ranchu that swims level and one that floats.
Schedule and amount
Two or three small feeds a day, each what the fish finish in about two minutes. Young fish growing hard can take four. Adults in cool water, under 60 °F, need only one small feed a day or every other day. A ranchu will always act starving; ignore it. Skip a day if any fish floats or the water tests high in nitrate.