Coral care
Coral care comes down to a handful of things done consistently: suitable light and flow, stable water, sensible placement, and a little food. Get those right and most corals will settle in, colour up and grow. This guide covers the routine that keeps a reef tank healthy.
Light
Most reef-building corals get a large share of their energy from the algae living in their tissue, which photosynthesise. That makes lighting central to coral care. Match the intensity and spectrum to the corals you keep, and keep the photoperiod consistent. When you move a coral, or change the light, do it gradually so the coral can adapt rather than bleach.
Different corals want different amounts of light. A coral placed too high can be over-lit; the same coral low in the tank may get too little. Use placement, not just the fixture's settings, to fine-tune.
Flow
Water movement brings food and oxygen to corals and carries waste away. It also keeps sediment from settling on them. Aim for varied, random flow rather than a single strong jet, and adjust so that soft corals sway without being battered and SPS colonies get brisk movement across them.
Water quality and stability
Corals tolerate a suitable range of conditions better than they tolerate swings. The goal is not a perfect single reading but a steady one:
- Salinity. Keep it consistent and mix salt water the same way for changes and top-ups.
- Temperature. Stable tropical temperatures, with no sudden shifts.
- Nutrients. Enough to feed the system, not so much that algae take over. Test rather than guess.
- Minerals. Stony corals use calcium and carbonate to grow, so keep an eye on what the tank consumes and replace it.
Placement
Give each coral a spot that suits its light and flow needs, and leave room between colonies. Many corals defend their space, and some extend sweeper tentacles, so a little distance prevents stinging. Mount frags securely on rock where they will not be knocked over by fish or maintenance.
When something looks wrong, change one thing at a time and wait before changing another. Chasing a problem with several adjustments at once makes it hard to know what helped.
Feeding
Light feeds the algae inside the coral; many corals also capture small food from the water. Target-feeding a suitable food can support growth, but it adds nutrients, so feed sparingly and keep testing. Filter feeders such as some soft corals benefit from fine food in the water column.
Pests and problems
Watch for pests that arrive on new corals, and inspect and dip new additions as the seller advises before they go in the tank. Receding tissue, a coral that will not open, or a sudden loss of colour are reasons to check water, light and flow in that order. For a first coral, the beginner corals guide covers the hardiest choices.
Finding reef stores in Canada
- Aquarium stores in Ontario
- Aquarium stores in British Columbia
- Aquarium stores in Alberta
- Search the whole Canadian directory
Coral care: common questions
What is the most important part of coral care?
Stability. Corals cope with a suitable range of conditions far better than they cope with rapid swings. Keep salinity, temperature, and mineral levels steady, and change one thing at a time.
How do I know if my coral is healthy?
Look for full colour, extended polyps during its active period, and steady growth or encrusting onto the rock. A coral that stays closed, loses colour or has receding tissue is signalling that something in the tank needs attention.
How often should I feed corals?
Many corals get most of their energy from light through the algae in their tissue, so feeding is often a supplement rather than the main diet. Target-feed sparingly if you choose to, and watch water quality so the extra food does not build up.
Why is my coral losing colour?
Colour loss can follow a sudden change in lighting, a temperature or salinity swing, or poor water quality. Correct the cause and keep conditions steady; the coral may recover its colour slowly over time.
Where can I get advice on coral care in Canada?
A good local reef store is the fastest source of advice for your area and water. Browse the Rainforest Reef directory by province and city, and use the saltwater and coral label to find reef-focused shops.
Keep reading
General information only. Confirm care needs and livestock availability with a local reef store.