Zoa (Zoanthid) Coral: Description and Care for Aquariums
Description: Zoanthid corals, commonly known as Zoas, are a popular group of soft corals that belong to the family Zoanthidae. These corals are known for their bright colors, easy care, and fast growth, making them a favorite for reef aquarium enthusiasts. They consist of numerous individual polyps that form a mat-like structure. Each polyp is made up of a central mouth surrounded by tentacles, and the color can vary widely—ranging from greens, blues, reds, purples, and even multicolors.
There are two main types of Zoas:
Zoanthids – These are the more common types and are often characterized by their large polyps and vibrant colors.
Palythoa – These are similar to Zoanthids but tend to be larger, with some species being capable of releasing toxins.
Care for Zoanthid Corals in an Aquarium:
Lighting: Zoas generally prefer moderate to bright lighting. They are photosynthetic and thrive under LED or T5 lighting, with around 100 to 250 PAR (photosynthetically active radiation) levels. Too much light can cause them to become stressed, while too little light can hinder their growth and coloration. It’s essential to adjust the lighting intensity to the needs of your Zoas, depending on their location in the tank.
Water Flow: Zoas appreciate moderate water flow. Too strong of a current may cause the polyps to retract, while too little flow can lead to detritus accumulation around the corals, potentially causing infections. A gentle to moderate flow that provides some movement without blasting them with water is ideal.
Water Parameters: Zoanthids are relatively hardy, but maintaining stable water conditions is crucial:
Temperature: 74°F to 80°F (23°C to 27°C)
Salinity: 1.023-1.025 specific gravity
pH: 8.1-8.4
Alkalinity: 8-12 dKH
Calcium: 400-450 ppm
Magnesium: 1250-1350 ppm
Nitrate: Below 10 ppm (for optimal growth)
Phosphate: Below 0.03 ppm (Zoas are sensitive to high phosphates)
Feeding: While Zoanthids can get the majority of their nutrients from light through photosynthesis, they will also benefit from occasional direct feeding. You can feed them marine snow, zooplankton, or reef pellets using a turkey baster. This helps encourage faster growth and vibrant coloration.
Placement in the Tank: Zoanthids are often placed at the bottom or middle of the aquarium, where light and flow conditions are optimal for their needs. They can spread across rock structures or substrates, making them great for covering large areas of the tank. However, you should avoid placing them under strong direct light or intense flow unless they are adapted to those conditions.
Tank Mates: Zoanthids are peaceful corals, making them compatible with other non-aggressive tank mates like soft corals, LPS corals, and fish. However, they should not be placed with aggressive species that may sting or compete for space, such as some large SPS corals. Additionally, palytoxin, a toxin released by some species of Zoanthids (specifically Palythoa), can be harmful to humans, so be cautious when handling them.
Fragging and Propagation: Zoanthids are easy to propagate by fragmenting. You can cut the polyps from the mat with a sharp blade, then glue them onto small pieces of live rock or frag plugs. They grow relatively quickly, so a few frags can soon lead to a dense colony.
Pests and Troubleshooting:
Zoanthid colonies can sometimes suffer from zoanthid eating nudibranchs, which are small slugs that feed on the coral tissue. Inspect your Zoas regularly for any signs of damage or pests.
Aiptasia anemones may also target Zoanthids. Keep an eye on the tank and remove any pests as soon as you see them.
Summary: Zoanthid corals are relatively easy to care for, making them perfect for both beginner and experienced reef keepers. By maintaining stable water conditions, proper lighting, and water flow, you can enjoy the vibrant colors and rapid growth of Zoas in your aquarium. Regular feeding and pest control will also help ensure the health of your Zoanthids.