Abstract
The histopathological observation was made on diseased elvers and anguilletes infected with Edwardsiella tarda. Diseased fish showed a swelling accompanying with minute hemorrhages and often perforation either in the liver or kidney region of the trunk. Histopathologically the disease could be classified in two forms as in the case of big eels.
1) Interstitial nephritis: In this form the degree of the suppurative reaction was weak as compared with the case with big eels. In the early stages of the disease small necrotic lesions appeared in the hematopoietic tissue of the kidney. In the advanced stages necrotic lesions developed into large ulcers. In the ulcerative lesions bacterial multiplication and liquefaction of the involved tissues were very marked. Metastatic lesions were common in the various organs.
2) Hepatitis: In anguilletes, a large liquefactive lesion appeared in the liver in the advanced stages. In elvers small abscesses were observed in the liver in the early stages. In the advanced stages a large ulcerative abscess was formed in the liver, and suppurative peritonitis and omentitis spreaded. The spleen, thymus and hematopoietic tissues were hyperplastic.
