How to Add Corals to an Aquarium

The intricate texture and bright colors of coral reefs come from the presence and activities of tiny coral animals. Corals also create a living landscape in a marine aquarium. Because corals are living creatures, not decorations, introducing them to a tank requires some preparation and care if the corals are to survive. An ever-increasing variety of corals are available in the pet trade, but not every species is suited to every marine aquarium. Bear in mind that corals are animals and behave like animals, not plants. They sometimes exhibit highly aggressive behavior, so position them carefully.

Things You'll Need

  • Large aquarium with light, filter and heater
  • Live sand
  • Live rock
  • Guides to marine aquarium corals and fish
  • Plastic bowl
  • Small cup
Show More

Instructions

    • 1

      Cycle your tank and introduce live sand and live rock. Turn heating and filtration equipment on and conduct regular water changes, but do not introduce any animals for at least a month.

    • 2

      Acquire corals suited to the temperature and water parameters of your tank. For example, if you are planning a tropical marine tank, which tends to be the most colorful, choose tropical corals whose water chemistry needs are similar to those of the fish you plan to buy. Detailed information about the needs of aquarium fish and coral species is available in specialist guidebooks, online and from marine biologists or hobbyists.

    • 3

      Fill a large plastic bowl with tank water and place in a warm room.

    • 4

      Place the bags with the corals in the bowl to acclimatize them. In the tank, they are likely to sink to the bottom, making the acclimation process difficult. Position the bags so that the tops are above the water in the bowl.

    • 5

      Open the bags and remove a little water with a small cup and discard. Replace with tank water. Repeat this process every 10 minutes over a period of an hour or more, until the bags contain mostly tank water. This is necessary, because sudden changes in water chemistry can shock or kill corals.

    • 6

      Knot or fasten the bags closed as tightly as you can and drop them into your tank. Leave for half an hour to allow the temperatures to equalize.

    • 7

      Remove the corals from their bags, handling them by the base, and position each species of hard coral at least 6 inches from each other in the tank. Corals might be sessile -- they are immobile after the larval stage -- but they can also be aggressive. Many coral animals have long, venomous tentacles, and a coral can easily kill its neighbors. Some corals extend creeping filaments to eat nearby animals.

    • 8

      Place slow-growing soft corals as far away from fast-growing species as you can, preferably at opposite ends of the tank. As with plants, fast-growing corals can overwhelm slower species nearby.

    • 9

      Switch the tank lights on after the introduction of the corals. Light supports the growth of symbiotic algae, from which corals derive most of their nutrients. Light also encourages the development of phytoplankton, and in turn zooplankton, that many corals catch to supplement the nutrients from the algae.

    • 10

      Introduce algae-eating invertebrates, such as snails, after a few days. These creatures help to control excessive attached algae growth.