The Safety of SLICE (0.2% Emamectin Benzoate) Administered in Feed to Fingerling Rainbow Trout

Abstract

SLICE (0.2% emamectin benzoate [EB]) is an in‐feed treatment that has been shown to be effective and safe for controlling infestations of several ectoparasitic crustacean copepods and branchiurans in a variety of seawater‐ and freshwater‐reared fishes. Although the safety of EB (in a pre‐SLICE formulation) for use with seawater‐reared Rainbow Trout Oncorhynchus mykiss has been demonstrated, the safety of SLICE for freshwater‐reared Rainbow Trout has not. Consequently, we conducted a trial to evaluate the safety of SLICE for freshwater‐reared Rainbow Trout when administered in feed at a dose of 0 (0×), 50 (1 × the maximum proposed therapeutic dose [1×]), 100 (2×), or 150 (3×) μg of EB·kg of fish body weight (BW)−1·d−1 for 14 d (2 × the proposed 7‐d treatment duration). Medicated feed was prepared by top‐coating commercially available feed with SLICE. Rainbow Trout fingerlings (mean TL ± SD = 7.4 ± 0.7 cm; mean weight ± SD = 4.4 ± 1.2 g) were stocked into 57‐L flow‐through tanks at 20 fish/tank. Diets were randomly assigned to four replicate tanks per treatment; fish in four additional, nontrial tanks were fed control diets and were weighed weekly to calculate the proper feeding quantities. Throughout the trial, water quality was maintained within ranges suitable for Rainbow Trout culture, fish were fed the assigned feeds at 4% BW/d divided equally between three feedings, and fish behavior was characterized as normal. Fish in the 0×, 1×, and 2× exposure groups consumed all of the offered feed at least 92% of the time, whereas fish in the 3× exposure group consumed all of the offered feed 75% of the time. No fish died, and gross and microscopic fish health evaluations revealed no chronic toxicity patterns. Based on these results, we conclude that there is an adequate margin of safety associated with administering SLICE‐medicated feed to fingerling Rainbow Trout at the proposed therapeutic treatment regimen of 50 μg EB·kg fish BW−1·d−1 for 7 d.

Effect of Graded Levels of Dietary Emamectin Benzoate on Immunity, Enzyme Activity, and Withdrawal Period in Labeo rohita Juveniles (Hamilton, 1822)

“…Considering the results, the differences between weight gains were not found to be significant (p > 0:05) and which is supporting the findings of Kilercioglu et al [24] where rainbow trout was administered at 50 μg EB kg -1 fish daily for 7, 14, and 21 days. After thorough investigation, we have come to end that no augmentation of growth in EB fed fish groups compared to control fish after 21 days of feeding which corroborate with earlier studies in rainbow trout and Atlantic salmon reported by few distinguished authors [20,25]. In addition to it, Siavash et al [26] also found that there was no mortality, or any difference in body weight and length between the controls and treated fish when rainbow trout was treated with another closely related drug i.e., ivermectin at 100 μg kg -1 intraperitoneal (IP) injections.…”

Oral administration of an antiparasitic agent emamectin benzoate persuades dose-dependent histoarchitectural alterations in Nile tilapia Oreochromis niloticus (L.)

“…The oating pelleted diets lasting in the tank 60 min after each feeding were siphoned into a pre-weighed vessel, dried overnight, and weighed. The feeding behaviour based on the feed consumed by the sh was noted daily and given numerical scores on a vepoint scale (Bowker et al 2013). The mortalities, sh behavioural changes like lethargy, aggressive and subdued feeding, position in the water column, equilibrium loss, uncharacteristic pigmentation or discolouration, gasping for air, ashing, hyperactivity, and other gross and dermal lesions were observed daily.…”

“…The histopathological changes in different organs of EB-dosed O. niloticus were evaluated based on the severity in comparison with control. The major changes were identi ed and given a qualitative assessment score using an ordinal scale, according to the percentage alteration of the tissue due to damages from its normal architecture (Bowker et al 2013). The investigational protocols ful lled the ethical guidelines including observance of the legal requirements of India (CPCSEA 2021).…”

A Review of Salinity's Impact on Relevant Aquatic Drug Approval Technical Sections

“…Emamectin benzoate is a compound that has safety data for the same species in both freshwater and salt water. In freshwater-held Rainbow Trout, no mortalities or signs of toxicity were observed after 14 d of oral treatment at a rate of 150 μg•kg body weight (BW) −1 •d −1 (3× the recommended dose and 2× the recommended treatment duration; Bowker et al 2013). In saltwater-held Rainbow Trout that were fed at 0, 100, 250, and 500 μg•kg BW −1 •d −1 (equivalent to 0, 2, 5, and 10× the recommended dose rate for treatment of sea lice Lepeophtheirus salmonis) for 7 d, there were no mortalities during the treatment or posttreatment periods (Roy et al 2000).…”