  Herbig-Haro objects (HHOs) are caused by outflows from young objects. Since
the outflow relies on mass accretion from a circumstellar disk, it indicates
ongoing growth. Recent results of infrared observations yielded evidence for
disks around brown dwarfs. This suggests that at least a certain fraction of
brown dwarfs forms like stars. Thus, young sub-stellar objects might cause HHOs
as well. We present selected results of a general survey for HHOs based on
DSS-II plates and CCD images taken with the Tautenburg Schmidt telescope.
Numerous young objects could be identified due to their association with newly
detected HHOs. In some cases the luminosity is consistent with very low-mass
stars or close to sub-stellar values. This holds for L1415-IRS and a few
infrared sources embedded in other dark clouds (e.g., GF9, BHR111). The
question on the minimum mass for outflow activity is addressed.
