A comparative study on the sensitivity of selected freshwater fishes against triclosan exposure

Abstract

Triclosan, a broad-spectrum antimicrobial agent, which is widely used in several pharmaceutical and personal care products, has been known to pose adverse impacts on various groups of aquatic organisms, including fish. The present study aimed to compare the sensitivity of five selected freshwater fishes toward triclosan exposure. The acute toxicity or median lethal concentration (LC₅₀-96 h) of triclosan determined using probit analysis was 1.76 mg L⁻¹ in Anabas testudineus, 448 µg L⁻¹ in Danio rerio, 700 µg L⁻¹ in Gambusia affinis, 1.35 mg L⁻¹ in Oreochromis mossambicus, and 750 µg L⁻¹ in Pseudetroplus maculatus. Based on the length–weight relationship, the lowest condition factor, or K value, was recorded in Danio rerio (0.931) while the highest value was observed in Anabas testudineus (2.343) indicating negative allometric growth. Similarly, the weight of fishes and gill weight declined significantly (p < 0.05) in their respective LC₅₀-96 h groups with concomitant alterations in the rate of oxygen consumption denoting respiratory distress. Triclosan exposure also resulted in the modification of fish behavior and histomorphological damage in gill tissues. The alterations in all parameters tested were more prominent in Danio rerio and thus considered the most sensitive species, while Anabas testudineus comparatively tolerated the toxicant to some extent. The study provides the baseline data that variation in the length–weight relationship is one of the major factors that influences the toxic effects of triclosan on the selected freshwater fishes.

Keywords:

• Triclosan
• acute toxicity
• oxygen consumption
• behavior
• histopathology

Author contributions

NR and NJ carried out the experiments, summarized and discussed the results, and prepared the manuscript. KCC planned the study, performed the statistical analysis, interpreted the results, and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.