Introduction
Expression of the small, non-rayed adipose fin
has been conserved evolutionarily by eight
orders of euteleost fishes (Nelson 1994; Reimchen
and Temple 2004), including the Siluriformes
(catfishes), Stomiiformes (dragonfishes),
Osmeriformes (smelts), and Salmoniformes
(salmon and trout). The adipose fin has been
used widely by systematists in species descriptions
(Helfman et al. 1997), used to distinguish
between otherwise similar species (Dahlberg
and Phinney 1967; Martinenz 1984), and is
frequently excised from hatchery produced