Effect of Temperature on Maturation, Spawning and Pigmentation of Xiphophorus helleri (Swordtail)

Abstract

This study assessed the impact of varying water temperatures on spawning, maturation, and pigmentation in Xiphophorus helleri (swordtail) over a period of sixty days. Four temperature treatments were set up at 21°C (T0), 24°C (T1), 27°C (T2), and 30°C (T3), with ten fish per tank using a 25-litre aquarium. Continuous aeration and thermostatic control maintained stable conditions. The daily water exchange ensured cleanliness by removing leftover feed and excreta. Among the treatments, 27°C (T2) showed the best reproductive performance. This temperature yielded the highest Gonadosomatic Index (GSI) for females (9.60±0.009) and males (7.83±0.008), as well as Hepatosomatic Index (HSI) values (1.47±0.008 for females). T2 also had the best spawning rate (21.85±2.10) and fry production (30.00±0.816), along with the most advanced oocyte maturation stages (vitellogenic oocytes). In terms of skin pigmentation, carotenoid levels were also highest at 27°C (2.92±0.170), with the best survival rate observed at 95.00% for this treatment, though survival differences across treatments were statistically non-significant (p>0.05). The current study affirmed that temperature is a pivotal factor in regulating spawning, maturation, and the enhancement of pigmentation in swordtails.