Dispersed fluorescence (DF) spectroscopy is used to explore the rovibrational structure of highly excited S-0 formaldehyde (H2CO). A narrowband laser excites formaldehyde molecules to a single S-1 rovibronic quantum state, and the resulting fluorescence is dispersed with a monochromator. DF spectra of ten vibrational levels with excitation in nu(2), the carbon-oxygen stretch, and nu(4), the out-of-plane bend, have been recorded, and the effective A, B, and C rotational constants are extracted. Five of the effective A rotational constants and seven of the effective B and C rotational constants are new to the literature. The dependence of these effective rotational constants on vibrational state are both calculated and discussed with regard to both the present and previous experiments. Particular attention is given to the manner in which that the effective A rotational constant depends on increasing excitation in nu(4) due to the strong A-axis nu(4)/nu(6) Coriolis interaction. For states where upsilon(2) is less than two, quantitatively accurate values for the nonlinear dependence of the A rotational constant on quanta in nu(2) and nu(4) is achieved by a simultaneous consideration of the strong A-axis nu(4)/nu(6) Coriolis interaction and the 1(1)<->4(2), 1(1)<->6(2), and 5(1)<->2(1)6(1) Fermi interactions.