STUDY OF LENGTH-WEIGHT RELATIONSHIPS AND CONDITION FACTORS OF SOME FISH SPECIES

Résumé

This review investigated the length-weight relationships (LWR) and condition factors (K) of Tilapia zilli, Tilapia mariae, Oreochromis niloticus, Barbus occidentalis and Barilius loati from Lower Usuma Reservoir in Abuja. Two thousand four hundred and fifty two (2,452) fish samples were collected for morphometric measurements. The results obtained showed that the growth pattern of the fish species had negatively allometric growth with b values range from 1.4 to 2.3. There was significant difference between LWR (P<0.001). There were strong correlation (0.86 – 0.73) between the length and weight of all the species, except Tilapia mariae which was weakly correlated (0.54). The condition factor (K) range from 1.06- 2.02, these were an indication that the fish species were thriving very well in the Reservoir. Futhermore, LWR and K of 5 fish species in Nkoro River Niger delta were reviewed. The exponential equation for the LWR were: Ethmalosa fimbrata (Wt= 0.0162 X Tl 3.199) and Cynoglossus senegalensis (Wt = 0.0326 X Tl 3.508). All species studied exhibited isometric growth pattern with the value of b = 3 except S. maderensis and C. senegalensis with value of b =3.6 and 3.5 respectively that exhibited positive allometric growth. The value of K ranged from 0.92 to 0.99 for Ilisha. africana to C. senegalensis). There was difference in the condition factors for the monthly K for E. fimbrata (0.85±0.015) and I. africana (0.96±0.061). LWR and K of Clarias gariepinus, in Kiri reservoir had a b value of 3.80 which indicated the fish species had allometric growth pattern. Monthly K range from 0.65 - 1.21 with a mean value of 0.78±0.09 and 1.04±0.12. Condition factors of the C. gariepinus were not in a good condition of wellbeing.