In-feed emamectin benzoate abuse affects the biological responses and erythrocytes of Nile tilapia Oreochromis niloticus

Abstract

In aquaculture, drugs are often abused to accomplish disease control without considering the negative effects on fish health. This study aimed at elucidating the pernicious effects of in-feed antiparasitic drug emamectin benzoate (EB) abuse on the haemato-biochemistry and erythro-morphometry of healthy Nile tilapia Oreochromis niloticus. The fish were fed EB at 50 μg (1×) and 150 μg/kg biomass/d (3×) for 14 d as against the recommended 7 d and periodically assessed the blood parameters. A significant dose- and time-dependent reduction in feed intake, survival, total erythrocytes (TEC), monocytes (MC), hemoglobin (Hb), hematocrit (Ht) and mean corpuscular Hb concentration were noted. The total leukocytes (TLC), thrombocytes (TC), lymphocytes (LC) and neutrophils (NC) markedly augmented. The EB-dosing altered the fish physiology by enhancing the glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and creatinine and reducing the calcium, chloride and acetylcholinesterase (AChE) levels dose-dependently. The fish recovered within 4 weeks in the 1× group post-dosing but persevered in the overdosed group. The erythro-cellular and nuclear dimensions were reduced with the increase in dose and normalized after the cessation of dosing, except for nuclear volume. The erythro-morphological alterations were more prominent in the overdosed group. The results implied the pernicious effect of oral EB medication on the biological responses of fish if abused.

Keywords:

• Fish culture
• Nile tilapia
• ectoparasites
• parasitic drug
• medicated feed
• fish health

Acknowledgments

The authors thank the Vice-Chancellor, West Bengal University of Animal and Fishery Sciences, Kolkata for providing the necessary facilities for carrying out this work.

Ethical approval

This study was performed in compliance with the guidelines of the Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), Government of India. The ICAR, Government of India, New Delhi approved the experimental protocols under the All-India Network Project on Fish Health (F. No. CIBA/AINP-FH/2015-16 dated 16.7.2015).

Author contributions

RD: Performed the wet laboratory experiments, laboratory investigation, data generation, statistical analyses, interpretation of the data and writing-original draft preparation; TJA: Conceptualization, methodology, project administration, supervision, resource mobilization, writing-reviewing and editing; JS, and AB: Performed the wet laboratory experiments, laboratory analysis, data generation and data curation; PKP: Conceptualization, methodology and funding. All authors agreed with the results and conclusions.

Data availability statement

The data supporting this study’s findings are available on request from the corresponding author.

Additional information

Funding

The research was supported by the Indian Council of Agricultural Research (ICAR), Government of India, New Delhi under the All-India Network Project on Fish Health: [Grant F. No. CIBA/AINP-FH/2015-16] dated 02.06.2015.