Growth, physiological and immune responses of Arapaima gigas (Arapaimidae) to Aeromonas hydrophila challenge and handling stress following feeding with immunostimulant supplemented diets

Abstract

The current study tested the efficacy of a dietary immunostimulant additive (Aquate Fish™ ®) on the growth performance, and on the physiological and immune responses of Arapaima gigas. Two trials were carried out: a feeding trial for 30 days with the experimental diets and a challenge trial for 7 days, in which fish were bacterial challenge (Aeromonas hydrophila) following by 60 s handling stress. During the feeding trial, fingerlings were fed diets supplemented with 0 (control), 6, 9 and 12 g Aquate Fish™ ® /kg diet. Dietary supplementation did not influence feed intake, feed conversion and condition factor, but increased the final biomass, number of erythrocytes, thrombocytes, leukocytes, lymphocytes, monocytes, hemoglobin, glucose, globulins and plasma triglycerides in fish fed at a concentration of 12 g/kg diet. After bacterial infection, mortality occurred only in fish fed control treatment, whereas respiratory burst of leukocytes, number of leukocytes and lymphocytes increased in fish that received 12 g of dietary supplementation. The results indicated that dietary supplementation with 12 g of Aquate Fish™ ® improved biomass and immunity performance of A. gigas fingerlings, without negatively affecting blood biochemical parameters.

Trichlorfon is effective against Dawestrema cycloancistrium and does not alter the physiological parameters of arapaima (Arapaima gigas): A large Neotropical fish from the Amazon

“…are also considered highly pathogenic because they have been responsible for causing high mortalities on arapaima fish farms, even with low and moderate parasite loads in Brazil (Santana et al, 2017), Peru (Morey et al, 2019) and a public aquarium in Denmark (Buchmann et al, 1994). It is noteworthy that its deleterious effects are more accentuated in the initial arapaima production stages (larvae and juvenile) (Dias et al, 2019), when they undergo several morphophysiological changes and adaptations to the aquatic environment (Alcântara et al, 2019;Frommel et al, 2021).…”

Immune disorders induced by improper use of dietary immunostimulants in aquatic animals: Research progress and prospective solutions by targeting gut microbiota

“…Moreover, the addition of proper levels of immunostimulants in the diet of aquatic animals affected the functions of nutrition, absorption and intestinal immunity positively 18–20 . Currently, the use of different types of immunostimulants including, chemical synthetic reagents, 21 bacterial derivatives, 22 fungal derivatives, 23,24 polysaccharides, 19,25–27 animal and plant extracts, 28 nutritional factor 29–32 as aquafeed additives were increased in aquatic animal feed 33 . Among them, polysaccharide immunostimulants have been widely used in aquafeed and studies revealed that they are important to promote the growth and immune function of aquatic animals.…”