Length-Weight Relationship of the Reed Fish, Erpetoicthys Calabaricus (Smith, 1866) In Ibikpe Creek

Background and Objective: Considering the “near threatened” status of E. calabaricus, consequent upon habitat degradation from anthropogenic perturbations, and total lacuna of literature and data on the growth and reproductive biology of the species, there was dire need to research on aspects of its ecology. Thus, this study was carried out in other to compute data on length weight relationship the species.

Materials and Methods: Six hundred and thirty four specimens were analyzed. Fish samples were obtained by sampling bi-monthly between April, 2013 and March, 2014. Samples were immediately preserved in 10 % formalin solution for laboratory analysis. Specimens were measured with a measuring board (scaled to ± 1 mm) to the nearest 0.1 cm to obtain total length (TL) and standard length (SL) and weighed on a top loading electronic meter balance (scaled to ± 0.01 g) to the nearest 0.00l g to obtain total weight (TW). The length-weight relationship was computed using the formular (TW = a (TL) b . Values of a and b were estimated by least square linear regression analysis using double-log transformed on length and weight data according to the formular: Log TW = log a + b log TL. Parameters of this relationship were computed for each sex, month and season.

Results: Regression analysis showed positive correlation between total length and total weight (r = 0.8931, p < 0.001) with an exponential relationship thus: TW = 0.004645 TL 2.6903accounting for variation (r2 ) in weight. The value of the length exponent (2.6903) in the length-weight regression which was different from the standard cube (3) value indicated negative allometric growth.

Conclusion: Findings suggests that as the fish increases in length, the body shape becomes “thinner” due to the negative impact on its environment. 

Keywords: Length-weight, regression, allometric, relationship, seasonal, analysis.