We present three fold symmetric microstructured fibers and their application potential for customized single mode supercontinuum generation. In our microstructured fibers we simultaneously achieve high nonlinearity and single mode operation by increasing three cladding air holes, which are next to the core. Selectively modified microstructures allow a large degree of freedom in the dispersion profile design. With the use of sub nanosecond pump source at the wavelength of 1064nm we show, that the designed microstructure provides various ways of generating a unique flat and broadband spectrum. •Experimental results for customized supercontinuum generation in visible and/or infrared spectra ranges.•Single mode operation, nonlinearity and dispersion control by three fold symmetry fibers.•Increased degree of freedom in supercontinuum design by loss dispersion and nonlinearity control.