Unlike most marine species that are
pelagic spawners, damselfish just as the clownfish, are substrate spawners which means they lay their adhesive eggs on the substrate. A male damselfish will establish a territory and then clean and prepare an area such as a piece of rubble that has a smoothed-walled crevice, a coral surface, or a rocky ledge for the female to deposit her eggs on.
Once the spawning site has been prepared, the male will then try to attract a female into his territory to deposit her eggs. The male engages in a number of tactics to entice the female to approach involving color changes and excited swimming movements, and in some species emiting clicking sounds. Once the female enters the spawning site, she will deposit up to 20,000 tiny oval adheasive eggs on the prepared smooth surface and then leave. The male will then quickly fertilize the eggs.
Each courtship and mating process takes about 10 to 20 minutes and a male may continue to mate with several additional females. In some species the male will tend the batches of eggs by fanning water across them with his fins, often picking out and eating dead eggs, presumably to prevent a fungus from developing that could threaten the whole batch. Some males provide no direct parental care except to protect the eggs from predators. In all cases, the male will aggressively and fearlessly guard his territory and the eggs from intruders, even fish much larger than himself.
The eggs will hatch in 3 to 7 days. The larvae then drifts away as plankton, feeding on the other
zooplankton and
phytoplankton for several to many weeks, depending on the species. A damselfish can take from 2 to 3 years or even longer to mature, with each species having its own timeframe.
