Evaluation of different stocking densities of tilapia (Oreochromis niloticus) in artisanal freshwater ponds in San Luis Talpa, La Paz, El Salvador

Abstract

The research was carried out at the Experimental and Practice Station of the Faculty of Agronomic Sciences of the University of El Salvador, located in the Tecualuya canton, municipality of San Luis Talpa, department of La Paz, in El Salvador, in the period of October 2019 to February 2020. The objective was to evaluate different stocking densities of tilapia (Oreochromis niloticus) in an artisanal pond, which was divided into two modules and these were subdivided into two cages of 2.5 meters wide, 3 m long and 1.15 m high), to distribute the treatments. The study was carried out under a randomized complete design; The treatments were: control or treatment 0 (T0) in which 5 tilapia/m3 were sown and 38 f ingerlings were placed in total; Treatment 1, 10 tilapia/m3 were sown, 75 fingerlings were placed; Treatment 2, 15 tilapia/m3 were sown and 113 fingerlings were placed; and treatment 3, 20 tilapia/m3 were planted, placing 150 fingerlings in total. Each treatment had 5 repetitions. The parameters that were measured were: weight and size or height of the tilapia. The sampling interval was every 14 days. The physical parameters (pH, temperature, alkalinity, hardness, turbidity, total dissolved solids, dissolved oxygen and electrical conductivity) and chemical parameters (arsenic, iron, lead, copper and zinc) were analyzed in the Laboratory of Agricultural Chemistry of the Faculty of Sciences. Agronomics of the University of El Salvador, and the microbiological analyzes were carried out in the Laboratory of Microbiological Quality Control of Food, Drugs and Water of the Center for Research and Development in Health (CENSALUD) of the University of El Salvador. The best average weight of the fish was obtained with a density of 5 tilapia/m3 (control or treatment 0) with 1,206 g (2.66 pounds); the highest growth or average size of the fish was obtained with the densities of 5, 10 and 20 tilapia/m3 (control or treatment 0, treatment 1 and treatment 3, respectively) with 18 cm and treatment 2 obtained less growth with 17 cm. The results for physical analysis: salinity (1%), OD (12.29 mg/l), STD (129.50 mg/l), conductivity E (292.33 µs/cm), pH (7.70), temperature 30.73 °C, turbidity (35 cm); heavy metals: arsenic (0.7861 ppm), copper (< 0.05 ppm) lead (4.2312 ppm), zinc (0.8928 ppm), iron (< 0.20 ppm).The physical-chemical analysis showed that the water used in the research was suitable for tilapia production.