Corals are animals, and they do need to eat. Thankfully, they are largely photosynthetic, so they derive a lot of food that they require directly from the strong lights that we put on our aquarium. The algae that lives in the tissue of photosynthetic corals produces the sugars and carbohydrates that corals need. However, that typically is not enough to sustain proper health and growth in corals.
If you want to see your corals not only live, but grow and multiply, you're going to need to feed them. The best way to feed them is after the lights are turned off at night, the corals go into predatory mode, where they put out their tentacles and they're trapping food particles that are in the water. That's the best time to feed.
There's a ton of food products on the market. Any of them are sized for the corals to grab right out of the water column. I find it's best when you're feeding, to unplug a few of the pumps, mainly the main system pump, so that the food stays in the aquarium. You can keep your circulation pumps on that are inside the aquarium, but you don't want the food to be filtered out by your protein skimmer in your mechanical filter in your filter sump.
So just keep like the vortex, or the [inaudible 00:01:19] working in the aquarium itself. A lot of people shut everything off, so they can directly target feed with a syringe, some of the more delicate corals. You can just use a turkey baster. Mix up the coral food inside a container of water, and then using the syringe, you can just inject it right above the coral so that the tentacles just get smothered and drowned in its food.
Otherwise, you can put it directly into the water column, and within five or ten minutes, the polyps usually capture enough of the food, so that you can turn the filter back on. Again, feeding the corals, same rules apply, you can't overfeed. You don't have to feed every day. Usually, two or three times a week is enough, and you'll see much better coloration and health in the tissues of the corals if you feed verses not feeding.
Having a lot of fish in the tank will also produce food for the fish as the fish release their waste, and as they eat the little bits of food will feed the corals indirectly. Having a delicately stocked aquarium, you don't want to overstock an aquarium, but having fish in the aquarium will benefit the corals, because it will produce food for the corals as well.