Caspian Journal of Veterinary Sciences

Caspian Journal of Veterinary Sciences

Comparative evaluation of the histopathological effects of florfenicol at a fixed therapeutic dose on the gill tissue of Oscar fish (Astronotus ocellatus) following oral and immersion administration

Articles in Press

Document Type : Original Article

Authors
Behnam Pedram 1
Amin Shahin zadeh 1
Seyedeh Ommolbanin Ghasemian 2
Leila Derakhshan 1
1 Department of Veterinary Medicine, Sho.C., Islamic Azad University, Shoushtar, Iran.
2 Department of Veterinary, Be.C., Islamic Azad University, Behbahan, Iran.
10.22034/cjvs.2026.582260.1067
Abstract
This study compared the histopathological effects of the antibiotic florfenicol on the gills of Oscar fish (Astronotus ocellatus) following oral and immersion administration. Thirty fish weighing 50 ± 5 g were divided into three groups (n = 10): an immersion group (florfenicol 10 mg/l for 60 minutes daily), an oral group (florfenicol 10 mg/kg body weight in feed for 7 days), and a control group without treatment. On day seven, gills were fixed in 10% buffered formalin. Sections were stained with hematoxylin–eosin (H&E)and examined microscopically. Histopathological lesions such as epithelial hyperplasia, edema, lamellar fusion, vascular congestion, necrosis, and structural changes were assessed using a semi‑quantitative scoring system (0–3 for each lesion). Statistical analysis was performed using Chi‑square and Kruskal–Wallis tests (p < 0.05). Results showed that florfenicol induced observable histopathological alterations in gill tissues at therapeutic doses, and lesion severity depended on the route of administration (p < 0.01). Controls showed no abnormalities. Oral treatment caused mild changes, including slight epithelial thickening and a moderate reduction of interlamellar space (score = 2). Immersion caused severe extensive epithelial hyperplasia, edema, vascular congestion, lamellar fusion, and structural disruption (score = 8). These findings suggested that oral administration of florfenicol may be safer than immersion for gill health in ornamental fish.
Keywords
Florfenicol
Gill histopathology
Immersion treatment
Oral administration
Oscar fish (Astronotus ocellatus)
Subjects
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Caspian Journal of Veterinary Sciences

Articles in Press, Accepted Manuscript
Available Online from 13 November 2026

  • Receive Date 18 May 2026
  • Revise Date 22 June 2026
  • Accept Date 22 June 2026