• Journal of Aquaculture
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• v.10 no.3
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• pp.281-288
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• 1997

We investigated the optimal concentratin of ethyl-p-aminobenzoate for the exfoliation and recovery of young abalone, Haliotis discus hannai in according to different water temperatures, for the purpose of preventing the damage of shell and muscle to ecfoliated from shelter. In the 14$^{\circ}C$ water temperature, young abalones were exfoliated after 16, 35, 35 and 35 minutes in 150, 100, 75 and 50ppm concentration of ethyl-p-aminobenzoate, and were recovered after 100, 60, 30 and 30 minutes, respectively. Exfoliation rate of abalone were 100% except for 50 ppm (80%) and recovery rate were 100% of all concentration. In the $18^{\circ}C$ water temperature, young abalones were exfoliated after 4, 4, 6, 8, 8 and 12 munutes in 300, 200, 150, 100, 75 and 50ppm concentration of ethyl-p-aminobenzoate, and were recovered after 210, 180, 90, 60, 30, 20 and 20 minutes, respectively. Exfoliation rate of abalone were 100%, and recovery rate were 100% except for 200 and 300ppm (90%). In the $24^{\circ}C$ water temperature, young abalones were exfoliated after 8, 10, 10 and 12 minutes in 150, 100, 75 and 50ppm concentration of ethyl-p-aminobenzoate, and were recovered after 70, 50, 30 and 20 minutes, respectively. Exfoliation and recovery rate of abalone were 100%. In the 18$^{\circ}C$water temperature, exfoliation rate that treated with freshwater during 20 minute were 80, 50, 30 and 5% in 100, 75, 50 and 25% of fresh water, and recovery after 60, 15, 10 and 2 minutes, respectively and recovery arate were 100% except of r 100% freshwater. In this study, we suggest the reslults that the exfoliation and recovery by ethly-p-aminobenzoate were more effected in $18^{\circ}C\;and\;24^{\circ}C$ of sea water temperature than those of $14^{\circ}C$. The optimal concentration of ethyl-p-aminobenzoate was 50ppm at those water temperature. We raised 20 individual of young abalones at water temperature of $16^{\circ}C$ in the 1$\ell$ o ftnk and checked the variatin of dissolved oxygen (DO) by respiration of abalones that treated with 75ppm of ethyl-p-aminobenzoate. Before anesthetizion, DO were 6.17~6.20mg/$\ell$ and slowly decreased. But after 60 minutes, DO decreasing were stopped in 5.42~5.46mg/$\ell$. On the other hand, the control was continuously decreased and 5.27mg/$\ell$ after 60 minutes. The heartbeats of abalones were 33~45/minute in the water temperature of $18^{\circ}C$, but that treated with 100 ppm concentration of ethyl-p-aminobenzoate during 60 minutes, was 0/minute. And heartbeats of recovered abalones from anesthetizion were 29~43/minute.

• Journal of fish pathology
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• v.2 no.2
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• pp.99-108
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• 1989

Anaethetics are needed for handling fish, especially for transportation, tagging and grading. Among them, MS-222 has been popular in aquaculture since it has an excellent anaesthetic effect. However, MS-222 is more expensive than other chemicals. Benzocaine (Ethyl-p-aminobenzoate) has a similar molecular formula and equivalent anaesthetic effect to MS-222, and is cheaper. The purpose of this study was first to compare anaesthetic effects (Benzocaine) under various conditions : temperature, concentration, pH and body weight. Second purpose was to compare actual anaesthetic effects at 50 ppm benzocaine at ambient temperature and pH for the grading of tilapia. The results of this study are as follows : 1. The effect of anaesthesia at $24^{\circ}C$ was better with low pH, that is 5.6 than high pH 6.6 and 7.6. 2. The anaesthetic effect was not different at different body weight form 11g to 1,350g. 3. The fish were anaesthetized in 4~10 minutes at 50 ppm benzocaine at temperature. $20{\sim}24^{\circ}C$ and pH 6.8~7.3 and recovered in 4~6 minutes when they were put back in the fresh water after 30 minutes anaesthesia. 4. Benzocaine was more sensitive at pH fluctuation than temperature. 5. Twenty four hour-TLm of Benzocaine was 50 ppm at $24^{\circ}C$, pH 6.8 when the fish were put back in the fresh water after 120 minutes.