Schreckstoff is known primarily from ostariophysans, but may not be unique
to that superorder. According to Moyle & Cech's ichthyology textbook, it may
be found in other fishes (but it doesn't say which ones).
For Schreckstoff to be released, the skin must be broken. So it appears
doubtful that a fish can release it just when it's simply stressed or
disturbed.
Schreckstoff can be detected by closely related species.
Perusing the literature I get the impression that Schreckstoff is a poorly
known, poorly studied phenomenon. The degree of Schreckstoff-iness varies
between species, and is more prevalent in turbid waters where vision is
limited.
Chris Scharpf
Baltimore
/-----------------------------------------------------------------------------
/"Unless stated otherwise, comments made on this list do not necessarily
/ reflect the beliefs or goals of the North American Native Fishes
/ Association"
/ This is the discussion list of the North American Native Fishes Association
/ nanfa_at_aquaria.net. To subscribe, unsubscribe, or get help, send the word
/ subscribe, unsubscribe, or help in the body (not subject) of an email to
/ nanfa-request_at_aquaria.net. For a digest version, send the command to
/ nanfa-digest-request_at_aquaria.net instead.
/ For more information about NANFA, visit our web page, http://www.nanfa.org