Gambusia appear to tolerate higher salinity levels (up to 35‰) than zebrafish (max 25‰), confirming previous reports. Gambusia species are known to live at low salinities (b15‰). However, some populations living at salinities up to 25‰ have been found (Renfro, 1960). Moreover, Gambusia affinis has been demonstrated to tolerate the acute transfer from fresh water to 19.5‰ (Chervinski, 1983) and the chronic exposure (7 days) to salinity levels of 39‰ and 58.5‰ (with survival rate of 65% and 50%, respectively) (Al-Daham and Bhatti, 1977). Concerning Danio rerio, a species that is considered to
be tolerant and well adapted to very low salinities (~ 35 μM NaCl)