Caesionidae: K III A9

Caesio xanthalytos Hollerman, Connell & Carpenter, 2013

Yellow-sash fusilier


Egg diameter in µm

Number of oil globules

Diameter of oil globule in µm

Yolk texture

Perivitelline space

Position of oil globule at hatch

Gut length   at eye- pigment stage








42% of NL



Egg: Black dots appear on the embryo, in 2 rows dorsally. On the oil globule, they are ventral, and usually densely packed, making the oil globule appear black on a white background (A1). The embryo has a pale yellow/amber hue on a white background. Incubation is 35-40 hours. *The PVS can be wider than usual in some batches of eggs. These eggs often sink when about to hatch.

Larva: This larva was separated from the previous one (KIIIA8), by the absence of a line of black on the anal tube (B). At 4 days, the larva develops a dark line of pigment over the gut (D). C: 1 day, D: 2 days, E: 4 days (24°C).

Many attempts to rear this common egg, were unsuccessful. Thirty-nine larval DNA barcode sequences are currently available, and match 7 locally collected adults.

Past egg presence records in this complex are clearly confused, and even going forward, it is difficult to identify every egg collected (see comments in KIIIA8). Nevertheless sufficient material has been barcoded, at least to enable me to create new pages, showing larval images of each of the species mentioned above, in cases where particular batches of eggs yielded barcodes. Careful attention to detail appears to be paying off, with better separation of C. xanthalytos and P. xanthura in samples since 2009. In the meantime, egg counts of KIIIA8 and KIIIA9 will continue to be combined. Of a total of 88 larval barcodes of the 3 main species in this complex in BOLD, 41 were P. xanthura, 8 were P. sordida and 39 were C. xanthalytos. One barcoded as Pterocaesio marri.


This was the 5th most common egg off Park Rynie, though boosted by an extraordinary catch of 19669 in June 2009, which barcoding showed to be C. xanthalytos. The fact that this stands out (blue graph) suggests the overall pattern is from the summer spawning Paracaesio zanthura. The egg was only seen once in the DHM samples, in June, which points to C. xanthalytos, known to be quite common there. At Park Rynie, the egg has shown an increasing presence, after being virtually absent in the first three years (white graph). In the Park Rynie linked samples, the eggs were dominant offshore (76%, if the June 2009 catch is excluded), indicating spawning inshore of kob (LIIIA8). This is consistant with my observations of this species, which is most commonly seen on the Aliwal Shoal (15-25m water depth) and surrounding reefs down to 30m. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.

Linked samples