一、河蟹急性中毒。此类毛病有二种情况。一是有毒因子因为侵害强度太大,在较短的时间内,通过河蟹的鳃、三角膜,使河蟹背甲后缘胀裂出现假性“蜕壳”,或三角膜呈红、黑泥性异色,或河蟹的腹脐张开下垂,四肢僵硬而死亡。二是有毒因子在较短时间内,通过水草、人工饲料的连带,经由 A crab acute poisoning. There are two cases of such problems. First, the toxic factor because of the infringement intensity is too large, in a short period of time, through the gills of the crab, the triangular membrane, so that the crab carapace posterior margin fissure appear pseudo “molt”, or triangular cornered red, black muddy Heterochromatic, or crab belly umbilical open sagging, stiff limbs and death. Second, the toxic factor in a relatively short period of time, through the aquatic plants, artificial feed, through