Histopathology of bullminnows, Fundulus grandis Baird & Girard, infected with a non-haemolytic group B Streptococcus sp.

Abstract. Histopathological changes in bullminnows, Fundulus grandis Baird and Girard, experimentally infected with a non-haemolytic group B Streptococcus sp. were studied. Following experimental exposure to the Streptococcus sp. approximately 40% of the fish developed exophthalmia, dropsy or petechial haemorrhage along the abdomen. The exophthalmic eye showed haemorrhage with neutrophil infiltration. The liver was oedematous and hepatocytes were atrophied, accompanied by a decrease in glycogen and increases in vacuolization, hyaline droplet degeneration and necrosis. The spleen was congested and cells of the sheathed artery were necrotized.