  We present a modified version of the Koide formula from a scalar potential
model or from a Yukawaon model, based on scalar fields set up in a nonet
representation of the SU(3) flavor symmetry in the Standard Model. The Koide's
character, which involves the Standard Model fermion mass ratios, is derived
from the vacuum expectation value of the nonet field in either model. The
scalar potential in the scalar potential model or the superpotential in the
Yukawaon model is constructed with all terms invariant under symmetries. The
resulting Koide's character, which is modified by two effective parameters, can
fit the experimental mass data of charged leptons, up quarks and down quarks.
It offers a natural interpretation of the Standard Model fermion mass spectrum.
