Nephroblastoma in Two Siamese Fighting Fish Betta splendens

In 2005 and 2008, renal nephroblastomas were diagnosed in two adult male Siamese fighting fish Betta splendens. In both cases the masses effaced approximately 90 percent of renal tissue and histopathologically, were composed of a triptych of diagnostic features, to include: nests of cells suggestive of blastema, a primitive mesenchyme as well as an epithelial component forming glomeruloid structures. To our knowledge, these cases represent the first reports of nephroblastoma in Siamese fighting fish.