SEASONAL VARIATION OF PHYSICOCHEMICAL PARAMETERS AND LENGTH-WEIGHT RELATIONSHIP OF SELECTED FISH SPECIES FROM RIVER DONGA, NIGERIA

Abstract

An 18-month study (March 2018 to August 2019) investigated the seasonal variation of physicochemical parameters and
length-weight relationships of Clarias gariepinus and Oreochromis niloticus from River Donga. Physicochemical
analysis revealed stressful conditions in both dry and wet seasons, with phosphate (1.17-3.57 mg/l and 1.36-2.73 mg/l),
ammonia (0-0.37 mg/l and 0-0.33 mg/l), and turbidity (2.67-76.25 mg/l and 11.67-121.25 mg/l) levels indicating stress.
Length-weight relationship analysis of 524 fish samples revealed b-values ranging from 0.335-3.254 and 1.440-2.862, and
K-values ranging from 0.481-0.803 and 1.298-2.460 for C. gariepinus and O. niloticus, respectively. Results revealed
negative allometric growth (b<3) for all O. niloticus and some C. gariepinus, as well as positive allometric growth (b>3)
for male and female C. gariepinus in the dry season. Seasonal trends in condition factor (K-value) indicated that both rain
fed and dry conditions favoured the wellness of O. niloticus. The high coefficient of determination (R ) values suggested
that fish weight was largely determined by length. The study highlights the importance of length-weight relationships and
condition factor in evaluating fish growth and well-being, and underscores the need for sustainable fisheries management
practices to ensure the long-term health of River Donga's fish populations.