Silurian period
placoderms (an ancient jawed fish)
During the Ordovician period, the first land plants evolved, as well as the first jawless fish, jawed fish, and arthropods like trilobites. This period also saw the emergence of the first coral reefs.
If you are asking what era the fish ORIGINATED, then your answer is the Cambrian Period, which was during the Paleozoic Era (544-245 million years ago). They started off as invertebrates, however. The first vertebrate that was a fish was the jawless fish in the Ordovician period. The first vertebrate that was a fish was the jawed fish in the Silurian period.
The first jawed fish appeared during the Silurian Period on the geological timescale.
there were aracnids, jawed fish,eurypterid and land plant
During the Silurian period, significant events included the diversification of jawed fish, the colonization of land by plants and invertebrates, and the formation of coral reefs. This period also saw the development of the first forests and the evolution of early arthropods.
fish
pterygotus, brontoscorpio,jaekelopterus,cephalaspis, cameracaras,endoceras,stromatopora.
eating other fishs
The answer to this question is fish as fishes were the first invertbrates to evolve.
Fish first evolved from work-like chordates around 500 million years ago. The first fish were small and jaw-less. They filtered food through holes where the mouth would be. Eventually these fish developed jaws and many of them started hunting other fish and animals. That is how modern fish diversified.