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本試驗係探討福馬林對鯉魚的急性毒與藥浴福馬林後鯉魚體內甲醛的殘留，以及藥浴福馬林對魚隻血液生化值之影響。由急性毒的試驗結果顯示，在20及30 °C水溫環境下，鯉魚置於福馬林溶液中96 hr之半致死濃度分別為126.44及101.69 ppm，顯示福馬林在30 °C時對鯉魚的毒性較強。在甲醛的蓄積殘留方面，為求與一般福馬林藥浴的方式一致，將鯉魚分別施以福馬林250 ppm藥浴1 hr、100 ppm藥浴2 hr及25 ppm長時間藥浴，另以未經福馬林處理者為對照組。殘留試驗結果顯示，不論福馬林藥浴的濃度高低，在短時間內鯉魚肌肉所含的甲醛量有明顯提高，而經144 hr後與對照組則無顯著差異；在長時間藥浴的25 ppm 組魚體內的甲醛含量較高，且在20及30 °C達到高峰的時間分別為48及24 hr，但不論溫度高低，回復到背景值的時間亦為144 hr。在施以不同福馬林藥浴處理後，各處理組魚隻的血容積比、血紅素及血漿總蛋白濃度與對照組間並無顯著差異，但高濃度藥浴組魚隻的血糖值高於對照組，然而25 ppm長時間藥浴組在藥浴後24 hr的血糖值反而顯著高於對照組；此外，不論溫度高低，250 ppm藥浴1 hr的魚隻在藥浴後24 hr的血容積比顯著高於對照組。本試驗結果表明，不同福馬林藥浴方式均在藥浴後144 hr回復到背景值，且各組魚隻之血紅素與血漿總蛋白濃度不受藥浴福馬林之影響。

In this study, we investigated the acute toxicity of formalin (a 37% formaldehyde solution) and formaldehyde residue in the muscle of common carp (Cyprinus carpio) exposed to different formalin concentrations for various periods. The effects on some hematological parameters of the carp were also examined. The acute toxicity test revealed that the 96-h LC50 values of formalin for carp reared at 20 and 30 °C were 126.44 and 101.69 ppm, respectively. The practical therapy of formalin for fish was considered in the formaldehyde residue study; therefore, carp reared at 30 or 20 °C were treated with 250 ppm formalin for 1 h, 100 ppm for 2 h, and 25 ppm for long-term exposure. Fish with no formalin treatment served as the control group. Formaldehyde in the muscle was analyzed after 1 h for the 250-ppm group and 2 h for the other three groups, and the analysis continued every 24 h after the first sampling. Results showed that formaldehyde in the muscle increased in the first samples after being exposed to various formalin treatments, and the level of formalin in treated fish was significantly higher than that of the control group. Furthermore, formaldehyde in the muscle of fish at 30 and 20 °C treated with 25 ppm for the long-term exposure reached a peak at 24 and 48 h, respectively. However, the formaldehyde concentrations of treated fish gradually decreased before returning to the background level after 144 h in each group. Hematocrit, hemoglobin, and total plasma protein did not significantly differ among any groups after various formalin treatments. However, plasma glucose levels in fish treated with formalin at 250 ppm for 1 h and at 100 ppm for 2 h were significantly higher than those of the control fish. Interestingly, this hyperglycemic condition was also found in fish treated with 25 ppm formalin for the long-term exposure after 24 h. It was also found that the hematocrit level of fish treated with 250 ppm formalin after 24 h was markedly higher than that of the control fish. The results of this study showed that the formaldehyde concentrations of all formalin-treated fish returned to the background level after 144 h, and non-significant changes in hemoglobin and total plasma protein among treatments were also observed during the period of formalin exposure.