Feeding Soft Corals in a Reef Tank

The Zooxanthellae Factor

Zooxanthellae-microscopic algae that live inside coral tissue-provide nutrients through photosynthesis, but primarily carbohydrates (sugars and starches). Corals also need:

• Proteins for growth and tissue repair

• Lipids (fats) for cell structure
• Vitamins for metabolic function
• Amino acids and trace elements

These nutrients come from multiple sources in a healthy reef: uneaten fish food, fish waste, bacteria, and the natural plankton-rich environment.

Active Feeding: More Than Photosynthesis

All soft corals, even those with zooxanthellae, actively capture food particles from the water column. They eat:

• Zooplankton (copepods, brine shrimp larvae, rotifers, mysis shrimp)
• Phytoplankton (microscopic algae particles)
• Bacterioplankton (bacteria and organic detritus)

• Dissolved organic molecules absorbed through their polyp tissues

In the ocean, soft corals naturally extend their tentacles at night when plankton abundance peaks. In a home aquarium, they'll learn to feed during the day if food is regularly offered.

Do You Actually Need to Feed Soft Corals?

This is the question that stumps many hobbyists. The answer: it depends on your coral species and your tank setup.

Corals That Thrive Without Supplemental Feeding

Some soft corals, like Zoanthids, grow and multiply in a reef aquarium with only the nutrients from a reasonable fish population and ambient organic matter. No special feeding required. These corals essentially "survive" on the incidental food their fish tankmates provide.

Corals That Benefit (or Require) Regular Feeding

Other soft corals-particularly those with lower photosynthetic capacity, or species from nutrient-rich natural habitats-simply do not thrive without regular supplemental feeding. These corals may appear pale, grow slowly, or stop reproducing if not fed.

The Growth and Health Difference

Most soft corals fed on a regular basis will grow faster, display richer coloration, and appear visibly healthier than their unfed counterparts. Even hardy corals benefit from supplemental feeding, though they won't starve without it. The trade-off is management: overfed tanks accumulate excess nutrients, triggering algae blooms and water-quality problems.

Key principle: In a new reef with no algae issues, target-feeding corals on a schedule is a low-risk way to boost their growth. If your tank already has persistent algae problems, wait until you've regained control before introducing regular coral feeding.

Best Foods for Soft Corals

Soft coral foods fall into several categories, each with its own strengths. Most hobbyists use a combination approach.

Plankton (Phytoplankton & Zooplankton)

Phytoplankton are nutrient-rich microscopic algae-dinoflagellates and diatoms-that naturally sustain a huge range of filter feeders in the ocean.

Zooplankton include:

• Copepods (small crustaceans)
• Rotifers (tiny roundworms)
• Brine shrimp nauplii (larvae)
• Mysis shrimp (small shrimp)
• Fish and mollusk larvae

Frozen Foods

Frozen coral foods are convenient and widely available. Common options include:

• Brine shrimp
• Mysis shrimp
• Chopped clams and shrimp
• Cyclops (small crustaceans)
• Krill
• Rotifers
• Silversides (tiny whole fish)
• Pre-mixed "coral food" blends (phytoplankton + zooplankton combinations)

Frozen foods are often less expensive than live cultures and store indefinitely. Many are also suitable for fish and other invertebrates, so a single package can feed your entire ecosystem.

Liquid Foods

Liquid feeds include live, preserved, and specialty blends. Look for:

• Live phytoplankton cultures
• Preserved copepods and rotifers
• Oyster eggs
• Proprietary "marine snow" formulations designed to mimic natural plankton blooms

Liquid foods are easy to dose and target-feed, though often pricier than frozen options.

Dry Foods

Dehydrated phytoplankton, zooplankton, krill, and proprietary blends are available but tend to be less digestible and nutrient-dense than frozen or live equivalents. Use them as a supplement, not a primary food source.

When and How to Feed: Feeding Schedules and Techniques

Optimal Feeding Times

In nature, corals extend their polyps and feed most actively at night when plankton levels peak. In your tank, most corals will learn to feed during the day if food is offered regularly.

Best practice: Feed your fish first. Feeding fish a thawed frozen food often stimulates corals to extend their feeding tentacles within minutes, a sign they're "primed" to accept food.

Should You Turn Off Powerheads When Feeding Corals?

Short answer: Yes, usually.

Before feeding, turn off your powerheads and circulation pumps to let the tank become still. When water is moving, food particles are swept past corals too quickly to be captured. Without current, particles settle and fall directly onto coral polyps where their tentacles can grab them.

Timing:

• Leave pumps off for 15 minutes to 1 hour while corals feed
• Gradually restart circulation after corals have stopped extending (watch for polyps to contract)
• Some experienced hobbyists eventually leave powerheads on once corals learn to intercept food mid-water, but beginners should err on the side of caution

Note: If your tank uses a mechanical filter (like filter socks), consider that uneaten food particles will fall into the overflow and be trapped in the sock. This captured food decays and becomes nutrient fuel for algae, so avoid overfeeding even with pumps off.

Do You Need to Turn Off the Protein Skimmer?

Yes, for at least 2 hours after feeding.

Protein skimmers are excellent at removing excess organic material-which means they'll also strip out much of the coral food you just added before polyps can consume it. Use a timer (such as a vacation timer) to automatically turn the skimmer off during feeding and back on after the corals have eaten their fill. This prevents you from forgetting to turn it back on and ensures the skimmer doesn't work against your feeding efforts.

Target Feeding: Precision Coral Nutrition

Target feeding gives you precise control over how much food enters the tank and ensures each coral gets a fair share. It's the best method for most hobbyists.

Equipment:

• Turkey baster
• Long medicine dropper
• Any similar gentle-flow feeding apparatus

Step-by-Step:

• Turn off all pumps and the protein skimmer
• Prepare your food: thaw frozen mysis shrimp and mix with a little aquarium water to create a slurry, or use liquid phytoplankton straight from the bottle
• Draw the food mixture into your baster or dropper
• Position yourself several inches away from the target coral
• Gently squirt small amounts of food toward the coral's polyps
• Watch the tentacles sense the food, capture it, and draw it toward the mouth
• The entire feeding process typically takes only a few minutes

Why it works: Instead of broadcasting food throughout the tank (where uneaten particles degrade water quality), you deliver food directly to the corals that need it most. This reduces waste and algae risk.

Water Quality and Common Feeding Mistakes

The Risk of Overfeeding

The biggest mistake is feeding too much. Uneaten food particles accumulate in the tank, breaking down into dissolved organic compounds that:

• Cloud water clarity
• Reduce oxygen levels
• Fuel algae growth
• Lower overall water quality

If your tank already struggles with algae, do not add regular coral feeding yet. Either target-feed very lightly or wait until you've reestablished algae control.

Maintaining Balance

A well-managed reef combines:

• Regular water changes (20-30% per month is typical)
• A strong protein skimmer (essential for removing excess organic matter)
• Live rock (provides natural nitrifying bacteria and macro-algae that compete with problem algae)
• A refugium (if you have one, it increases plankton production and nutrient export)
• Activated carbon (optional, helps polish water and remove organic compounds)

Learn more about testing your water parameters to ensure feeding efforts don't degrade your reef's chemistry.

Putting It All Together

Healthy, thriving soft corals are your best feedback. If your corals are:

• Growing noticeably over weeks and months
• Displaying vibrant, stable coloration
• Extending polyps fully and regularly
• Reproducing (if they're asexual species like Zoanthids)

...then your feeding strategy is working.

The golden rule: Good water quality, appropriate light, and the right foods are the pillars of soft coral success. Most hobbyists find that a combination of frozen mysis shrimp, live or preserved phytoplankton, and the incidental nutrition from fish food creates the best results with minimal algae risk.

If you're just starting out, begin with light target feeding once or twice per week using frozen mysis shrimp or liquid phytoplankton. Monitor your water quality closely (especially nitrate and phosphate). As you gain confidence and see how your tank responds, adjust frequency and portion size upward. It's far easier to add more food than to reverse an algae problem caused by overfeeding.