Sanjika, Opsaridium microcephalum, were collected from two sites (Nkhotakota and Chia)
along the southwestern shoreline of Lake Malawi. The sagitta of the otolith was
arrowhead-shaped with an obvious nucleus. Increments in the sagittae were observable
until the bases of the rostra but invisible in the rostra. The asteriscus was oval-shaped
with an ambiguous nucleus, leading to difficulty in identifying the first increment.
The lapillus was 'a'-shaped with an obvious nucleus and increments were observable from
the nucleus to the margin. The lapillus was therefore considered the most suitable
structure for interpreting daily growth increments in this species. The estimated hatching
months of fish based on lapilli increment counts were from November to July, suggesting
that this species has a long breeding period of at least eight months per year. The growth
rate of fish born in the rainy season (0.74 mm TL per day) was higher than those in the dry
season (0.56 mm TL per day). This growth difference was considered to be due to the
difference in water temperature in the lake.