Combined effects of surface area of periphyton substrates and stocking density on growth performance, health status, and immune response of Nile tilapia (Oreochromis niloticus) produced in cages

• Published in: Journal of applied phycology Vol. 32; no. 5; pp. 3419 - 3428
• Main Authors: Tammam, Marwa S., Wassef, Elham A., Toutou, Mohamed M., El-Sayed, Abdel-Fattah M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.10.2020; Springer Nature B.V
• Subjects: Alanine; Alanine transaminase; Albumins; Biomarkers; Biomedical and Life Sciences; Body composition; Cages; Cholesterol; Cyanobacteria; Defence mechanisms; Density; Dry matter; Ecology; Factorial design; Feed composition; Feed conversion; Feed conversion efficiency; Feed efficiency; Feeding experiments; Fish; Floating cages; Freshwater & Marine Ecology; Freshwater fishes; Glucose 6 phosphate dehydrogenase; Glucosephosphate dehydrogenase; Growth rate; Immune response; Immune system; Immunity; Immunoglobulin G; Immunoglobulin M; Juveniles; Life Sciences; Marine fishes; Oreochromis niloticus; Periphyton; Phosphates; Plant Physiology; Plant Sciences; Ponds; Proteins; Serum; Stocking; Stocking density; Substrates; Surface area; Tilapia; Triglycerides; Whitefish; Serum biomarkers; Hematology; Nile tilapia; Periphyton; Cage-fish farming; Stocking density
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-020-02136-x

A 4-month feeding trial was conducted to investigate the effect of surface area of periphyton substrates (PS) and stocking density (SD) of juvenile Nile tilapia, Oreochromis niloticus , on growth, major blood constituents, and some immunity biomarkers. Six treatments (T1–T6) were established in 18 floating cages (1 m 3 water each) fixed in an earthen pond for growing tilapia (1.12 ± 0.10 g), in a 2 × 3 factorial design experiment (2 SD × 3 PS). For T1, T2, and T3, fish were stocked at a rate of 70 m −3 with 1, 2, or 3 PS units (area: 0.7, 1.4, and 2.0 m 2 , respectively). For T4–T6, fish were stocked at 90 m −3 , also with 1, 2, or 3 PS units. All fish were fed a 20% crude protein supplemental diet. The best growth rates, feed efficiency, body composition, immune response, and overall health status were attained for T2 group with 70 fish m −3 in the presence of 2 PS units (1.4 m 2 ) followed by T5 with 90 fish m −3 plus 2 PS. Stocking density affected albumin while periphyton substrates impacted cholesterol, triglycerides, and alanine aminotransferase levels in fish serum. Meanwhile, total proteins and glucose-6-phosphate dehydrogenase were not significantly affected. Serum immunoglobulin (IgM and IgG) values were relatively higher in fish reared at 70 m −3 than at 90 fish m −3 indicating better immunity response. Periphyton biomass (dry matter, DM and ash-free DM) was lower in T2, than in other treatments, whereas periphyton populations belonged mainly to Chlorophyta (52–75%), Cyanobacteria (17–23%), and Charophyta (4–21%). Accordingly, the present study suggests that 70 fish m −3 and 2 PS units (surface area of 1.4 m 2 ) would be an optimal combination for the best growth, health status, and immunity response of juvenile Nile tilapia reared in periphyton-based cage system.