Influence of continuous illumination at increasing light intensities on the growth and survival of early stage Snubnose Pompano, Trachinotus blochii

The study investigated the influence of continuous illumination at increasing light intensities on feeding, growth, and survival of early-stage snubnose pompano,Trachinotus blochii, larvae from 1 to 10 days post-hatching (DPH). Fish larvae were exposed to 5 treatments with 3 replicates [T₁ - natural indoor 12 hours light (hL): 12 hours dark (hD), T₂ - 300-500 lux (lx), T₃ - 300-1000 lx, T₄ - 300-2000 lx, and T₅ - 300-3000 lx]. Newly hatched larvae were stocked at 15 ind. /L density and fed with enriched rotifers (Brachionus plicatilis; 50-250 µm) at 30 ind. /ml starting from 2 DPH. The number of rotifers in the digestive organ, feeding incidence, and total length of larvae were examined at 3-hour intervals from 0400 to 2200 hours (H) on 3 DPH, at 6-hour intervals from 4 to 5 DPH, and once on 8 DPH at 1000 H. The results justified that snubnose pompano was a visual feeder and exhibited diel rhythm within 24 hours of light, while larvae at natural photoperiod usually underwent diurnal rhythms. However, changing light intensity conditions from low to high levels altered the feeding behavior of the fish larvae. Better and consistent feeding and survival of larvae were obtained at moderate continuous illumination at increasing light intensities (300-500 lx). While higher light treatments (300-1000, 300-2000) can yield more remarkable fish growth, they adversely affect larval survival after 5 DPH. In conclusion, moderate continuous illumination (300–500 lx) promotes consistent feeding, resulting in a positive growth response and improved survival in early-stage snub nose pompano.