Effects of Different Substrates on Growth and Survival of Labeo victorianus (Pisces: Cyprinidae, Boulenger 1901) Fry towards Its Conservation along the Mara Basin

摘要

The study evaluated the role of different substrates on water quality, growth and survival of Labeo victorianus fry. Random sampling was used to select 225 fry, stocked at 100/m3 and fed on shell free artemia® (40% - 60% crude protein). Each treatment was carried out in triplicates using gravel and sand as substrates and water media without substrate (control). Growth and survival of the fry was monitored over 4 weeks period at a hatchery set-up. Physicochemical parameters were measured weekly while mortality was documented daily. Substrate type had an effect on water quality, growth and survival of fry. Dissolved Oxygen, growth and survival was higher in tanks under gravel substrate than sand and control while mortality was higher (22%) for sand (p ≤ 0.05) than gravel and sand treatments. Fry in gravel substrate had the best growth response (1.77 ± 0.92 g) while control and sand recorded 1.57 ± 0.90 g and 1.45 ± 0.97 g respectively. In contrast, growth was homogenous during the first 2 weeks of the trial but gravel substrate fry significantly out-grew sand and control in the remaining 3 weeks. However, fry in sand and control experienced compensatory growth towards the end of the study. Therefore, gravel substrate enhances L. victorianus performance and is recommended in the introduction of the species into aquaculture and re-stocking back to the wild.