The circumglobal ocean sunfishes, Molidae (specifically Mola spp.), have long held the record for being the world’s most fecund vertebrates. This record is based on one 1.5m individual whose ovary was estimated to contain 300 million “small and unripe” ova (Schmidt 1921). Few data have been available to assess this claim of reproductive prowess since large gravid sunfishes (>1.5m TL) are rarely encountered and ways of describing fecundity are not standardized. This chapter reviews our current knowledge of sunfish reproduction and proposes an assessment of fecundity in terms of productivity. It offers additional insight through the histological examination of samples collected from geographically disparate regions including California and Japan, the east coast of the USA, and the Mediterranean (Italy and Portugal). Ovaries at different stages of sexual maturity from two different species of molid are examined--M. mola (35.5cm - 2.9m TL) and M. tecta (2.15m TL). From Kamogawa Japan, three additional large female Mola spp. (2.10m, 2.43m and 2.72m TL) are described along with the first known molid egg release from a 1m TL captive female at Kamogawa SeaWorld. A new record of 847 million ova in a single female (2.2m total length) is presented. Lastly, future research directions are detailed and discussed.