The Safety of Aquaflor (50% Florfenicol) Administered in Feed to Fingerling Yellow Perch

Abstract

Aquaflor is an aquaculture feed premix containing 50% florfenicol and is approved for use in more than 50 countries to control mortality in a variety of cultured fishes caused by diseases associated with infectious bacterial pathogens. As part of an effort to expand the current approval in the United States, we conducted a study to evaluate the safety of Aquaflor to Yellow Perch Perca flavescens when administered in feed at 0× (0 mg/kg), 1× (15 mg/kg), 3× (45 mg/kg), or 5× (75 mg/kg) the proposed maximum therapeutic treatment dose of 15 mg florfenicol·kg fish−1·d−1 for 20 consecutive days, 2× the proposed therapeutic treatment duration of 10 consecutive days. Fingerling Yellow Perch (7.8 ± 1.6 cm and 5.0 ± 3.4 g; mean ± SD) were stocked into flow‐through test tanks at 15 fish per tank, and treatments were randomly assigned to tanks in triplicate. At the end of the 20‐d exposure period, mean cumulative mortality in the 0× and 3× groups (6.7% for both) was greater than that in the 1× and 5× groups (2.2% and 0.0%, respectively); however, differences among the groups were not significant (P = 0.3741). Throughout the study, general fish behavior was characterized as normal, and fish consumed virtually all feed offered. Fish health and histology assessments revealed no signs or lesions associated with toxicity of florfenicol. In conclusion, there is an adequate margin of safety associated with administering Aquaflor‐medicated feed to fingerling Yellow Perch at the proposed therapeutic treatment regimen of 15 mg florfenicol·kg fish−1·d−1 for 10 d.

Assessment of haematological, histopathological, and serum biochemical responses in Oreochromis niloticus (L.) upon dietary florfenicol administration

“…In contrast, the 3X group recorded a 1.04-folds biomass increment. With the termination of dosing, the juveniles showed no abnormalities and increased interest in feeding, though insigni cantly, similar to a previous study (Bowker et al, 2013). The 1X group that received the therapeutic dose and dosage recorded 100% survival.…”

A global analysis on the systemic effects of antibiotics in cultured fish and their potential human health risk: a review

“…In summary, feeding, exposing or injecting fish with antibiotics cause various histopathological effects in vital organs such as liver, kidney, gills and intestine due to oxidative stress and their toxicity, suggesting impaired nutrition metabolism, gaseous exchange, osmoregulation and digestive functions. These results imply severe effects on fish physiology because both exposure to acute doses and chronic treatment of antibiotics caused deleterious histological effects (Rodrigues et al 2019), although a few antibiotics did not induce significant organ changes (Snieszko & Wood 1955;Gaunt et al 2003;Bakke-McKellep et al 2007;Topic Popovic et al 2012;Bowker et al 2013), highlighting antibiotic and fish species-specific damage. Since most cultured fish are more susceptible to secondary infections, the histopathological alterations may affect fish haematological parameters.…”

“…2012; Bowker et al . 2013), highlighting antibiotic and fish species‐specific damage. Since most cultured fish are more susceptible to secondary infections, the histopathological alterations may affect fish haematological parameters.…”

Maximum levels of cross‐contamination for 24 antimicrobial active substances in non‐target feed. Part 7: Amphenicols: florfenicol and thiamphenicol

“…In one study in yellow perch, dietary florfenicol supplementation at 15–75 mg/kg bw per day did not affect performance (Bowker et al., 2013 ), with tested levels of florfenicol being considered to be very high (15–75 mg/kg bw per day).…”

“…3.3.1.3.1.3. Yellow perch Bowker et al (2013) studied the safety of florfenicol (Aquaflor aquaculture feed premix containing florfenicol 50% w/w; supplied by Merck Animal Health, Summit, New Jersey) for yellow perch (Perca flavescens). A total of 180 ten-month-old fish was used; the antimicrobial was administered in feed at 0, 1,500, 4,500 and 7,500 mg/kg feed (calculated from the levels provided in the publication of 0, 15, 45 and 75 mg/kg BW per day; fish were fed at 1 % BW/day) during 20 consecutive days.…”