Sodium chloride against Dawestrema cycloancistrium in juvenile Arapaima gigas

Abstract

The aim of the present study was to assess the use of sodium chloride (NaCl) against monogenoid infestations in pirarucu (Arapaima gigas). Two assays were conducted with pirarucu juveniles, the rst comprising an in vitro exposure to 8; 9; 10 and 11 g.L − 1 NaCl and comparison to controls not exposed to NaCl, and the second, an in vivo exposure to NaCl at the same concentrations applied in the in vitro exposure. The best in vitro results were observed for one hour exposures at 9, 10 and 11 g.L − 1 NaCl, resulting in 60% and 100% parasite mortality, respectively. In vivo exposures to 8 and 10 g.L − 1 NaCl were 36 and 22% e cient, respectively, following two hours of exposure, with no mortality. Some dosedependent changes were observed in exposed sh, such as decreased hemoglobin and HCM values at the highest NaCl concentration compared to the other NaCl concentrations and the control group. More frequent gill tissue alterations were observed compared to the control group at the highest NaCl concentrations (10 and 11 g.L − 1 ). Decreased mean (p < 0.05) water pH values and increased mean electrical conductivity were noted compared to the control group. Our ndings suggest that NaCl exhibits low toxicity towards pirarucu and anthelmintic activity to the monogenoid Dawestrema cycloancistrium, directly in uenced by exposure time and concentration.

Levamisole hydrochloride as an anthelmintic against Neoechinorhynchus buttnerae in juvenile Colossoma macropomum

“…During this period, the fish were fed twice a day with commercial feed (36% CP) until apparent satiety until reaching ±100 g. Then, a new parasite sampling was carried out on 10 fish anaesthetized with eugenol (20%) and subsequently sacrificed to determine N . buttnerae parasite indices (Affonso et al, 2012, 2023). High parasite stimulation was observed, with a mean parasitic average infection intensity (AII) of 60.9 ± 39.2.…”

“…Previously analysed tambaqui juveniles (±80 g) free of N. buttnerae (Andrade-Porto et al, 2017), from a commercial fish farm, were stocked in a 50 m 2 excavated pond and cohabited with infected tambaqui (± 250 g) for 30 days at the INPA Aquaculture Experimental Station (National Amazonia Research Institute), in the state of Amazonas, Brazil. During this period, the fish were fed twice a day with commercial feed (36% CP) until apparent satiety until reaching ±100 g. Then, a new parasite sampling was carried out on 10 fish anaesthetized with eugenol (20%) and subsequently sacrificed to determine N. buttnerae parasite indices (Affonso et al, 2012(Affonso et al, , 2023.…”

“…Hemograms were determined from a whole blood aliquot from each fish, comprising haematocrit, haemoglobin content, mean corpuscular volume (MCV) (Ht × 10/Ert), mean corpuscular haemoglobin (MCH) (Hb × 10/Ert) and mean corpuscular haemoglobin concentration (MCHC) (Hb × 100/Ht) determinations and erythrocyte, leukocyte and thrombocyte counts (Claudiano et al, 2019). Plasma glucose was determined by the colorimetric enzymatic GOD-Trinder method (Affonso et al, 2012(Affonso et al, , 2023.…”