Investigations into the salinity tolerance of freshwater species
have been predominantly motivated by ecological concerns.
The studies made by Bringolf et al. (2005) and
Schofield et al. (2006) assessed salinity tolerance as barriers
to invasion for the flathead catfish Pylodictis olivaris and Goldfish
Carassius auratus, respectively. DiMaggio et al. (2009)
studied the evaluation of seminole killifish Fundulus seminolis
as a candidate for aquaculture. Killifishes (Cyprinodontiformes)
are particularly interesting because of their ability to
acclimate to different saline environments and represent useful
models for biological research. Osmosensitivity and salinity
detection are of high physiological interest. Fish have prolactin
(PRL) cells which are directly osmosensitive (Grau et al.,
1994). They also possess chemoreceptors, situated in the
pseudobranch that are connected to the central nervous system
(CNS), providing information on water salinity (Laurent and
Dunel-Erb, 1984). These participate in triggering the water
drinking mechanism in seawater fish. Many authors have carried
out research on the influence of water salinity on fish
development (Boeuf and Payan, 2001).