Fish in Focus:   Word in Focus Schreckstoff

Yellowfin shiner, Notropis lutipinnis
© William F. Roston

This Fish in Focus page is a little different, it's a Word in Focus

"Schreckstoff"

Minnows, like the yellowfin shiners in spawning coloration shown on this page, belong to a large and disparate superorder of fishes called Ostariophysi, which also includes suckers, loaches, catfishes, characins, knifefishes, and the electric eel, among others. One ostariophysan trait is the ability to produce a chemical substance called Schreckstoff (from the German words for fright and stuff). When an ostariophysan fish is bitten by a predator, special skin cells release Schreckstoff into the water. This sends a message to schoolmates and other closely related species to take a variety of escape actions.

Some ostariophysan fishes have lost their ability to produce Schreckstoff for adaptive reasons. For example, piranhas do not release an alarm substance since many of their prey are ostariophysans, and it wouldn't make sense for them to flee each time they bit into a fish.