Abstract: Both a method and apparatus are disclosed for incubating fish eggs. The incubator is specifically suited for eggs normally incubated by mouthbrooding. However, other brooding forms are equally well attended. The apparatus includes a cylindrical, screened container rotatably mounted about a horizontal axis and driven by a paddle wheel. The entire apparatus is sunk into a fish tank and air is supplied beneath the paddle wheel for continuous slow-speed rotation of the cylindrical container. The eggs are positioned within the container and allowed to slowly move by gravity as the container is rotated.