Extermination of the Parasites of Cultured Puffer by Domoic Acid

将被白纹伊蚊寄生的养殖河豚在添加250ppm软骨藻酸(DA)的海水中浸泡5min，或在含有100ppm软骨藻酸的淡水中浸泡20min。在洗澡实验中，河豚皮肤中PF的去除率(R)分别为80.0%和100%，远高于相同浓度的海藻酸和福尔马林。在FW洗浴中，10ppm和50ppm DA作用10-20min，Pf90%以上被去除；5ppm，20min，Pf71%被去除。用添加14-128ppm红藻氨酸(KA)的FW进行类似的实验，超过ppm，浸泡时间超过15min，R值达到100%。另一方面，从养殖的河豚身上取出6只四齿异弯藻幼鱼及其寄生部分(鳃)。其中两组沐浴在不含DA的SW中，其余的沐浴在加有100ppm DA的SW中。结果表明，前两种河豚在鳃上存活4小时以上，后4种在30分钟内从鳃上取出，4小时内死亡。用100ppm DA浸泡FW 20min的河豚血液检测结果均为正常，而以100ppm DA或ppm KA浸泡20min的FW标本均未检出DA和Ka3。由此可见，DA和KA是一种对Pf或Ht非常有效和安全的寄生剂。

The cultured tiger puffers parasitized by Pseudocaligusfugu (Pf) were bathed for 5 min in the seawater (SW) added with 250 ppm ofdomoic acid (DA), or for 20 min in the freshwater (FW) with 100 ppm DA. The removal rates (R) of Pf from the puffer skin during these bathing experiments were 80.0 and 100 %, respectively, the values being much higher than those of the same concentrations of Marine Sour and formalin. In case of FW bathing, more than 90 % of Pfwere removed at 10 and 50 ppm DA for 10-20 min, and 71 %, at 5 ppm for 20 min. When the similar experiment was performed using FW added with 14-128 ppm of kainic acid (KA),R reached to 100 % at more than 64 ppm with the bathing time of more than 15 min.On the other hand, six juveniles ofHeterobothrium tetrodonis (Ht) were picked out together with their parasitic part (the gills) from cultured puffers. Two of them were bathed in SW without DA, and the rest were in SW added with 100 ppm DA. As the results, both of the former two were alive on the gills for more than 4 hours, while the latter four removed from the gills within 30 min, and died within 4 hours.The results of blood test of the puffer specimens subjected to FW bathing at 100 ppm DA for 20 min showed that they are all normal, and no DA nor KAwas detectable by HPLC and LC/MS analyses from the specimens submitted to FW bathing at 100 ppm DA or 64 ppm KA for 20 min. From these results, it can be concluded that DA and KA are very effective and safe parasiticides against Pf or Ht.