Một số đặc điểm sinh trưởng và sinh học sinh sản của cá lia thia đồng (Betta sp.) ở huyện Đức Huệ, tỉnh Long An

Abstract

The present study investigated the growth characteristics, feeding habits, and reproductive biology of the wild Siamese fighting fish population (Betta sp.) distributed in Duc Hue district, Long An province, Vietnam. The study was conducted over four months, covering August - September 2024 (rainy season) and March - April 2025 (dry season), with samples collected once per month. Results indicated that Betta sp. was found in all communes of the Duc Hue district except Dong Thanh town, where habitat alteration due to urbanization may have contributed to local population decline or disappearance. The length-weight relationship was established as W = 0.018 L^2.587 (R₂ = 0.878). The regression coefficient (b = 2.587) was lower than 3, indicating negative allometric growth, suggesting a faster increase in length than in body weight. The mean relative length of the gut (RLG) was 0.42 ± 0.01, confirming its carnivorous feeding habit. Feeding analysis showed active carnivorous behavior, with approximately 80 - 92% of specimens exhibiting stomach fullness levels of ≥ 2. Feeding intensity was significantly higher during the wet season (χ² = 28.293, P = 0.005). Reproductive indices showed seasonal variation: mean gonadosomatic index (GSI) peaked during the wet season (females: 6.41 - 7.00%; males: 5.04 - 5.06%), indicating higher reproductive readiness in this period. Mean absolute fecundity (AFe) was estimated at 255 ± 29 eggs per female, and mean relative fecundity (RFe) was 531 ± 56 eggs per gram of female body weight. This study provides essential biological baseline data for the management and conservation of Betta sp. resources in the local area.