Sialic acids (Sia) are located at the outermost position of glycoproteins. They play a critical role in biological processes. The polysialyltransferases (polySTs) are enzymes producing Sia polymers (polySia). These are important for the brain development. In contrast, little is known about the role of polySia in fish ovaries. We investigated the distribution of the polySTs in teleosts and determined their expression levels in ovaries of two fish species. Furthermore, we observed polySia positive cells in ovaries. The results provide new insights into the role of polySia during oogenesis.