Length-Weight, Length-Length Relationships and Condition Factors of Three Schibid Catfishes from the Padma River, Northwestern Bangladesh

The present study describes the length-weight (LWR) and length-length (LLR) relationships, as well as the condition factors of the three important Schibid catfishes from the Padma River, northwestern Bangladesh, namely Ailia coila (Hamilton, 1822), Eutropiichthys vacha (Hamilton, 1822), and Neotropius atherinoides (Bloch, 1794). A total of 347 specimens were caught using traditional fishing gears from March 2006 to February 2007. For each individual, the total (TL), fork (FL) and standard (SL) lengths were measured using digital slide calipers. Individual body weight (BW) was also taken through a digital balance. The coefficient b of the LWR was close to the isometric value (b ≈ 3.000) in A. coila, although it suggested negative allometric growth in E. vacha (b ≈ 2.980) and N. atherinoides (b ≈ 2.900). The results also indicated that the LLRs were highly correlated (r^2 0.914; P 0.01). The equations of the condition factors for each species were best expressed by K= 100×(BW/ (TL^3.000) for A. coila, K= 100 ×(BW/(TL^3.000) for E. vacha, and Kn= BW/[(0.095×TL^2.899] and K= 100 ×(BW/(TL^3.000) for N. atherinoides. This study presents for the first time results on the total length-body weight relationships and on the condition factors of these catfishes from the Padma River.