Wikipedia has more on Ichthyophobia
Ichthyophobia is often caused by traumatic experiences involving fish, like getting bitten or stung by fish, or even bad experiences while fishing like the boat capsizing and being stranded at sea, which can lead to hypothermia. Ichthyophobes would not go in the water where there are fish because many of whom are afraid to get bitten by fish, and they would not fish.
Ichthyophobes would not eat fish possibly because they believe that eating fish or other marine foods may poison them, including that some fish may contain \.
Smelling fish or other smelling like fish from non-fish things could cause extreme anxiety.