I develop new methods for identifying and measuring tidal dwarf galaxies, using a sample of galaxies within Hi-rich groups that have no evidence of advanced major mergers. These groups are taken from the Survey of Ionization in Neutral Gas Galaxies (SINGG, Meurer et al., 2006), an optical follow-up survey to the HI Parkes All Sky Survey (HIPASS, Barnes et al., 2001). Fifteen of the fields contain four or more emission line galaxies and are named Choir groups. I detect new dwarf galaxies that

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... too small to be individually detectable in HIPASS; they are detectable in the SINGG narrow-band imaging because of their star formation and membership of these HI-rich groups. The Choir groups are compact, with a mean projected separation between the two brightest members of 190 kpc. They have comparable star formation efficiency (the ratio of star formation rate to HI mass) to the remaining SINGG fields. The Choir member galaxies also match the wider SINGG sample in their radii, Hα equivalent width and surface brightness. I define a new, more robust calibration for the metallicity diagnostic for identifying tidal dwarf galaxy candidates in the absence of tidal tails, based on the luminosity-metallicity relation with a consistent metallicity definition. Using that calibration, SDSS dwarfs fainter than MR = -16 have a mean metallicity of 12 + log(O/H) = 8.28 \(\pm\) 0.10, regardless of their luminosity. Tidal dwarf galaxy candidates in the literature are elevated above this at 12 + log(O/H) = 8.70 \(\pm\) 0.05 on average. Our hydrodynamical simulations also predict that tidal dwarf galaxies should have metallicities elevated above the normal luminosity-metallicity relation. I compare 53 star-forming galaxies in 9 of the Hi gas-rich Choir groups and find those brighter than MR ~ -16 to be consistent with the normal relation defined by the SDSS sample. At fainter magnitudes my sample has a wide range in metallicity, suggestive of varying Hi content and environment. Three (16%) of the dwarfs are strong [...]