Anaesthetic efficacy of eugenol on Flowerhorn (Amphilophus labiatus  × Amphilophus trimaculatus )

Abstract

Anaesthetic efficacy of eugenol was investigated on Flowerhorn (Amphilophus labiatus 9 Amphilophus trimaculatus). A total of 104 fish with average weights of 12 AE 2.5, 28 AE 5 and 53 AE 5.1 g were subjected to 25-200 mg L À1 eugenol and behavioural responses as well as induction and recovery times were recorded. Induction and recovery times were significantly affected by eugenol concentration as well as fish weight (P < 0.05). Generally, 49.9-127.3 s after exposure to 50-200 mg L À1 eugenol, fish reached stage 3 anaesthesia (suitable for general handling). Fish entered stage 4 anaesthesia (suitable for surgery and blood sampling) over 57.3-140.4 s post exposure to such concentrations. Recovery time was 91.7-312 s in all weight classes for all eugenol concentrations. Mortality (23%) was only observed in 12-g fish when were subjected to 200 mg L À1 eugenol. This study showed the behavioural response of Flowerhorn to anaesthesia and eugenol efficacy as an anaesthetic in this important ornamental species. The general quadratic equation revealed that concentrations of eugenol and fish size along with their interactive effects have significantly contributed to the model, with concentration recording the highest beta value in all models (b = À0.809, À0.818 and À0.909, P = 0.000). According to the results, minimum eugenol concentration to induce anaesthesia in less than 3 min was 50 mg L À1 .

Anaesthetic efficacy of eugenol on various size classes of angelfish (Pterophyllum scalare Schultze, 1823)

“…, Tarkhani et al. ). Similar to our results on angelfish with 1 g body weight, it has also been shown that 4.0 mg/L etomidate was able to anaesthetize 0.3‐2 g angelfish in 78 s and fish fully recovered in 240 s (Amend, Goven & Elliot ).…”

“…Finally, fish were transferred to freshwater aquaria to monitor potential mortality over a 24‐h period (Tarkhani et al. ). Table contained behavioural responses of fish at various anaesthetic stages; however, more details were illustrated elsewhere (Hoseini et al.…”

“…Particularly, such constraints encourage using less persistent and natural anaesthetics such as clove oil (Tarkhani et al. ).…”

“…Its anaesthetic efficiency has been reported for distinct ornamental fish species including Amphilophus labiatus × Amphilophus trimaculatus (Tarkhani et al. ), Pangasius hypophthalmus (Hoseini et al. ), Pterophyllum scalare (Mitjana, Bonastre, Insua, Falceto, Esteban, Josa & Espinosa ), Pomacentrus amboinensis (Munday & Wilson ), Danio rerio (Grush, Noakes & Moccia ).…”

“…The anaesthetic efficacy of eugenol was the subject of several studies on various fish species such as common carp, Cyprinus carpio (Hikasa, Takase, Ogasawara and Ogasawara ), rabbitfish ( Siganus lineatus ) (Soto & Burhanuddin ), fathead minnow ( Pimephales promelas Rafinesque, 1820) (Palić, Herolt, Andreasen, Menzel & Roth ), Common snook ( Centropomus undecimalis Bloch, 1792) (Bernardes Júnior, Nakagome, Mello, Garcia & Amaral Júnior ) and flower horn (Tarkhani et al. ).…”