Length-Weight, Length-Length Relationships and Condition Factor of Hypophthalmichthys nobilis Fingerlings from Bahawalnagar, Pakistan

Bighead carp (Hypophthalmichthys nobilis) is an economically important aquaculture species valued for its rapid growth and filter-feeding ability. Objective: To examine the morphometric parameters specifically the length–weight relationship (LWR), length–length relationships (LLRs), and condition factor of Hypophthalmichthys nobilis (bighead carp) fingerlings reared in hatcheries in Bahawalnagar, Pakistan. Methods: A total of 35 fingerlings were sampled. Morphometric measurements including total length (TL), standard length (SL), fork length (FL), head length (HL), and body weight (W) were recorded. The LWR was calculated using the formula W = aTLᵇ, and the LLRs were derived through linear regression between different length parameters. The condition factor (K) was determined using the Fulton’s formula. Results: The mean ± SD values for TL and W were 10.21 ± 0.52 cm and 9.53 ± 1.45 g, respectively. The LWR showed a negative allometric growth pattern with constants a = –1.5671 and b = 2.52, and a strong correlation (r = 0.887). Strong positive correlations were observed in LLRs: TL vs. SL (b = 1.03), TL vs. FL (b = 0.74), and TL vs. HL (b = 0.85). The mean ± SD condition factor was 0.89 ± 0.06, indicating moderately good fish health. Conclusions: This study presented updated, population-specific data on morphometric relationships and the condition factor of Hypophthalmichthys nobilis fingerlings in Pakistan. These findings provide a valuable baseline for region-specific stock assessments and contribute to informed, sustainable management strategies for bighead carp in hatchery settings.