I bestrode the carp, my shadow falling across their backs, but the fish ignored me. Their pink-rimmed mouths gaped roundly. Carp have low oxygen requirements, but they do need a little. These fish were so crazy for the oxygenated water flowing down from the marsh that a big predator like me mattered not at all to them. Salmon and shad are anadromous, swimming up from the sea to spawn.
Eels are catadromous, swimming down.
These carp were neither. They were paludromous, to invent a term. They were swimming marshward to survive. This very exigency the drying up of pools and puddles was what drove the evolution of the lungfish and walking fish and mudskippers, but great expanses of geological time were required for that. The carp had only days.