抄録
Some individuals among carps of one batch grow much faster than other in the same condition. We call them “Tobi-Koi” or Shoot-carps. They show characteristic asymmetry on the frequency curve of the body length of the batch. We calculated the skewness
Sk=1/σ3•1/N•∑fi(xi--x)3
and found that its value is larger than +1.5 in many cases in which the Tobi-Koi appears.
The frequency curves of the egg diameter, body length of hatched larvae and 8 days old post-larvae kept without feeding show approximately the normal distribution, but after 20 days culture fed with Cladocerans the Tobi-Koi individuals are found already.
