Evolved: Around 75,000 Yh (By 100,000 Yh)
Extinct: Not yet.
Location: South hemisphere ocean on the temperate to subtropical climate band.
Viable Habitat: Temperate to warm deep and shallow waters with sufficient prey. Usually found at the eutrophic zone or close to the eutrophic zone. May spend considerable time in shallow coastal areas, but passes through deep ocean in migratory crossings.
Size: Up to 1.5 m
Dietary Needs: Starts life on a diet of plankton and phytoplankton. As it grows it starts to eat other invertebrates that are larger than plankton such as prawns, and young or tiny fish and squid. Mature fish eat larger squid and fish prey.
Life Cycle: Spawning grounds no longer occur in upstream rivers, instead they occur in brackish waters or in low salinity bays with a lot of freshwater outlet. The "smolt" starts at the beginning of life. Once the alevin have progressed to fry they are already in the ocean and fully acclimated to the saltwater.
They have a competitive and predatory relationship with the squid. Young squid are eaten by larger older fish, and young fish are eaten by larger older squid. Cannibalism also occurs, making it a free-for-all. What's more they compete with the squid for prawns until they grow large enough to hunt nearly any animal they swim across.
Most of their life danger comes from the oceans. The breeding season is not as perilous as it was for their ancestors who had to migrate uphill. Young still have a high rate of mortality, but adults can live for decades.
Other: Their scales are broad and flat so that squid have less to get a grip of when attacking with their tentacles, which have grippers that can embed into flesh. It also minimizes damage done by other animals including other fish, and minimizes entry points for parasites. Flat scales are not the most aquadynamic solution (despite seeming like the intuitive solution), but they are fast enough to survive and catch the food they need.
Their shape allows them to glide through the water with low effort to propel themselves, allowing them to make great journeys across sea between lands. When travelling they keep a moderate pace but can swim faster in an instant if it spots food or a threat. It cannot sustain it's fastest pace for more than a few seconds however, just enough time to get out of the range of detection from some predators.