Pearse's mudskipper (Periophthalmus novemradiatus)

Biology

Dorsal spines (total): 9 - 11; Dorsal soft rays (total): 11-12; Anal spines: 1; Anal soft rays: 12 - 13. This is a sexually dimorphic species, with males possessing greatly elongate first spine of first dorsal fin, reaching eighth element of second dorsal fin when appressed; when preserved first dorsal fin brown or black with white distal edge, no spots; margin of first dorsal fin concave in males while concave to straight in females; second dorsal fin with two black bands, broader one located inframarginally and the other located medially, black spots basally on membrane between dorsal fin elements; pelvic fin with prominent frenum and inner rays fused for more than half of length. D1 modally IX; D2 modally I,12; A modally I,13; caudal fin rays modally 15 segmented rays, with first and last two rays unbranched; 62-67 lateral scale rows; 18-24 predorsal scales.

Source: FishBase, licensed CC BY-NC 4.0.