Essential oil from Ocimum basilicum improves growth performance and does not alter biochemical variables related to stress in pirarucu (Arapaima gigas).

Samantha Chung,Carlos H Da P Lemos,Carlos E Copatti,Daniel V Teixeira,Rodrigo Fortes-Silva

doi:10.1590/0001-3765202020181374

Abstract

Diet supplementation with essential oil from sweet basil Ocimum basilicum (EOOB) can increase fish growth. So, this study aimed to evaluate the effect of EOOB in the diet on growth performance and plasmatic variables of pirarucu juveniles (Arapaima gigas) submitted to stressful condition (stocking density of 7.56 kg m-3per tank and limited space). Four diets (in triplicates) were evaluated with increasing levels of EOOB (0.0 control; 0.5; 1.0; and 2.0 mL kg diet-1) over 48 days. Linalool was the major constituent of EOOB (54.19%). The addition of 2.0 mL EOOB kg diet-1 improved final weight, weight gain, specific growth rate, condition factor and feed conversion ratio; it also decreased plasma urea levels and increased plasma albumin and total proteins levels. Plasma glucose, cortisol, and acid uric levels were not influenced by the addition of EOOB to the fish diet. In conclusion, the addition of 2.0 mL EOOBkg diet-1 is recommended for pirarucu juveniles, due to improved growth performance, and this supplementation did not compromise the homeostasis of fish rearing in a high stocking density.

Highlights

Pirarucu (Arapaima gigas) is one of the largest freshwater fish species in the Amazon basin, an it is a new and promising species for cultivation in fish farms
A linear effect (p< 0.05) was observed between the essential oil from sweet basil Ocimum basilicum (EOOB) and thefinal weight (y = 1385.304 + 43.504x, R2 = 0.75), WG (y = 437.990 + 43.883x, R2 = 0.89), SGR (y = 0.784 + 0.069x, R2 = 0.98), CF (y = 0.184 + 0.027x, R2=0.94) and FCR (y = 1.940 – 0.223x, R2 = 0.90).according to the linear effect, pirarucus fed with 2.0 mL EOOB kg diet–1 increased their Final W, WG, SGR, and CF, and they decreased their FCR (Table II)
Juveniles fed with the 2.0 mL EOOB kg diet–1 presented significantly higher plasma albumin than those feed with 0.0 or 1.0 mL EOOB kg diet–1 and total proteins than those receiving other concentrations of EOOB in the diet (p< 0.05)

Summary

Introduction

Pirarucu (Arapaima gigas) is one of the largest freshwater fish species in the Amazon basin, an it is a new and promising species for cultivation in fish farms. This is due to the high marketability of its fillet, as well as its high rate of growth, rusticity and adjustment to artificial feeding (de Andrade et al 2007, Drumond et al 2010). High stocking density is commonly associated with an increase in the concentration of nitrogen compounds in the water, which can impair water quality and fish development and causes stress (Lemos et al 2018). The economic analysis performed by De Oliveira et al (2012) indicated that the aquaculture of pirarucu in cages at moderated stocking densities (0.26 kg m–3) and without space limitation showed better zootechnical

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