Title : Continuous illumination accelerates the metamorphosis of the late larval stage of snubnose pompano Trachinotus blochii Lacepede 1801
Abstract:
Snubnose pompano Trachinotus blochii is receptive to applying an artificial light system and extended day length (photoperiod). This study investigated the influence of continuous illumination at different light intensities on feeding, morphology, growth, and survival of late-stage snubnose pompano larvae from 16 to 35 DPH. Four light treatments (T2 – 500 lx, T3 – 1000 lx, T4 – 2000 lx, T5 – 3000 lx) provided within 24 hours were compared with a control treatment (T1 – natural indoor light; 12hL: 12hD). Larvae at 14 DPH were stocked at 2 ind. /L and acclimatized for two days before the experiment. Larvae were fed with a combination of artemia (Instar I; 400-600 μm) and an artificial diet three times a day from 16 to 35 DPH. Morphological observation and growth assessment were done daily using a stereo microscope. Survival was determined by counting all remaining fish after 35 DPH. Results indicate that late-stage snubnose pompano larvae are visual feeders and exhibit diel rhythm within 24 hours of light. In contrast, larvae at natural photoperiod typically undergo diurnal rhythms. Better growth, survival, and significantly higher percentage of metamorphosed larvae were achieved at 3000 lx than at lower light levels (500-2000 lx). Larvae at natural photoperiod (12hL: 12hD) had the least growth, survival, and metamorphosis.
Keywords: Trachinotus blochii, late stage, continuous illumination, metamorphosis
