We numerically study the Stokes eigen-modes in two dimensions on isosceles triangles with apex angle θ=π/3, π/2, and 2π/3 by using two spectral solvers, i.e., a Lagrangian collocation method with a weak formulation for the primitive variables and a Legendre–Galerkin method for the stream-function. We compute the first 6,400 Stokes eigen-modes. With 72 collocation points in each spatial dimension, the eigen-values λn for n ≤ 400 can be obtained with spectral accuracy and at least ten significant digits. We show the symmetry of the Stokes eigen-modes dictated by the geometry of the bounded flow domain. From the spectrally accurate data of the Stokes eigen-modes, the following features are observed. First, the n-dependence of the spectrum λn obeys the Weyl asymptotic formula in two dimensional space: λn=C1n+C2n+o(n). Second, for an isosceles triangle with legs of unit length, the θ-dependence of the spectrum λn can be accurately approximated by λn(θ)/λn(π/2) ≈ 1/(sin θ), as a consequence the volume-dependence of the coefficient C1 in the Weyl asymptotic formula. And third, a linear stream function-vorticity correlation is observed in the interior of the flow domain.