3a. Dorsal-fin height greater than length of head; pectoral-fin margin angular; nasal barbel
extends well beyond opercular margin . . . . . . . . . . . . . . . . . . . . .Paraplotosus butleri
(northern and western Australia, from Shark Bay to the Gulf of Carpentaria)
3b. Dorsal-fin height less than, or equal to, length of head; pectoral-fin margin rounded;
nasal barbel not extending beyond opercular margin, often falling far short of margin . . . . . _ 4