Since natural populations do not show this demographic, it was suggested that there may be an age-dependent shift in sex allocation from a female dominated population to a hermaphroditic population. This shift is somewhat similar to diandric protogynous hermaphroditism observed in other teleost fishes, particularly the Gobiidae. This study offers one possible explanation of how adult populations in Florida are overwhelmingly dominated by hermaphrodites. It remains for future study to determine whether the high genetic variability observed in natural populations is due to sexual reproduction by young adult fish, or to self fertilization by hermaphrodites. Mature eggs measure over 1 mm in diameter.
Adults commonly catch and eat spawned eggs as they are released.
Later in the season, adult fish generally lay more than 75 eggs. While some thermal buffering by land crab burrows undoubtedly occurred, it apparently was insufficient to protect R. marmoratus from the extreme cold, as specimens of this fish were not collected again for 8-17 months following the freeze. In addition to tolerating extremes in salinity and temperature, R. marmoratus also tolerates high sulfide levels. As such, it is generally found in areas depauperate of other fish species, such as crab burrows, stagnant pools and impounded ditches. The authors interpreted this unusual character to an epidermal or mucous reaction to high sulfide levels in the burrow.