Fish eggs hatch in a process called incubation, which can occur in several different ways depending on the species of fish. Mouthbrooding: Some species of fish, such as cichlids and anglerfish, will carry their eggs in their mouth until they hatch, providing protection and oxygen to the developing eggs. Demersal: Some species of fish lay their eggs on the bottom of a body of water, where they are guarded by the adult fish until they hatch. Pelagic: Other species of fish lay their eggs in the open water, where they are fertilized and then drift with the currents until they hatch. The exact time it takes for fish eggs to hatch can vary greatly depending on the species, water temperature, and other environmental conditions. Some species of fish may hatch in just a few days, while others may take several weeks or even months to hatch. After hatching, the newly-hatched fish, called larvae or fry, are usually small and vulnerable to predators. It is important for the adult fish to provide protection and nutrition to their offspring during this critical stage to ensure their survival and growth.