The bible only tells us that animals, birds, were to be taken on the Ark.We do not know how salty the sea was before the Flood. The Flood was initiated by the breaking up of the ‘fountains of the great deep’ (Gen. 7:11). Whatever the ‘fountains of the great deep’ were, the Flood must have been associated with massive earth movements, because of the weight of the water alone, which would have resulted in great volcanic activity.
Volcanoes emit huge amounts of steam, and underwater lava creates hot water/steam, which dissolves minerals, adding salt to the water. Furthermore,
erosion accompanying the movement of water off the continents after the Flood would have added salt to the oceans. In other words, we would expect
the pre-Flood ocean waters to be less salty than they were after the Flood.There are migratory species of fish that travel between salt and fresh
water. For example, salmon, striped bass and Atlantic sturgeon spawn in freshwater and mature in saltwater. Eels reproduce in saltwater and grow to
maturity in freshwater streams and lakes. So, many of today’s species of fish are able to adjust to both freshwater and saltwater.
Hybrids of wild trout (freshwater) and farmed salmon (migratory species) have been discovered in Scotland,2 suggesting that the differences between
freshwater and marine types may be quite minor. Indeed, the differences in physiology seem to be largely differences in degree rather than kind. The
kidneys of freshwater species excrete excess water (the urine has low salt concentration) and those of marine species excrete excess salt (the urine
has high salt concentration). Saltwater sharks have high concentrations of urea in the blood to retain water in the saltwater environment whereas
freshwater sharks have low concentrations of urea to avoid accumulating water. When sawfish move from saltwater to freshwater they increase their
urine output twenty fold, and their blood urea concentration decreases to less than one-third.Major public aquariums use the ability of fish to adapt
to water of different salinity from their normal habitat to exhibit freshwater and saltwater species together. The fish can adapt if the salinity is
changed slowly enough
als were taen on the ark