Development of Thai river sprat’s
myomere in yolk-sac larvae were not complete.
Figure 3a shows 37 developed myomere, with
opened digestive gut at 82%NL in yolk-sac larvae and moving to 59%TL in juvenile (Figure 3b-f).
Malanophore pigmentation occurred on brain,
anal-fin base and caudal-fin base after flexion
stage. The results were similar to those reported
by Termvichakorn (2003). The other pigments or
coloration might be lost from preservation by
neutralized formalin solution especially silver
write transverse-band, located from posterior gill
opening to caudal-fin base not visible from
preserved specimens. However, yellowish
coloration on caudal-fin base was visible from
some preserved specimens. In identification, Thai
river sprat larvae may be misidentified among
Boneo river sprat (Clupeiodes boneensis Bleeker,
1851) especially before post-flexion stage
specimens. It was a small clupeids fish found in
Pasak Jolasid reservoir but not in abundance.
However, Thai river sprat larvae could be
separated by the last two anal-fin rays detached
form the others (Whitehead, 1985 and Rainboth,
1996).