Developing embryos and newly-hatched larva are most sensitive and delicate of the stages in the life history of a fish. Therefore, great care must be taken to provide them with the proper incubating and hatching environment. Water temperatur, light, water quality, water flow, shock prevention, and type and size of the egg are very important considerations.
A wide variety devices are used for incubating fish eggs and closely correspond to egg type. Egg mats are primarily for adhesive eggs, e.g. catfish and common carp eggs. A tray-type incubator were originally designed to hatch of non-adhesive, lay in gravel bed of the eggs and can be injured by movement during incubation, e.g. trout and salmon eggs. Modified this type could be used to hatch of floating eggs, e.g. gouramy egg. Fish eggs that non-adhesive and require constant movement are commonly incubated in conical shaped tanks or jar where water flows into the bottom or top of the container, eggs gentrly suspended and constantly tumble in the lower portion of the jar, e.g. tilapia egg.
recapped from W.Kitimasak