Apart From The Zooxanthellae How Else Do Corals Feed

Keeping a reef tank is one of the most rewarding challenges in the aquarium hobby. We often focus so much on high-end LED lights that we forget our corals are actually living, breathing animals.

You might be wondering, apart from the zooxanthellae how else do corals feed to maintain those vibrant colors and fast growth rates? If you have ever felt like your corals are “stalling” despite perfect lighting, you are in the right place.

In this guide, I will take you through the fascinating world of coral heterotrophy. We will explore how corals hunt, what they eat, and how you can supercharge their growth with the right feeding routine.

The Dual Nature of Coral Nutrition

To be a successful “reefer,” you have to understand that corals are mixotrophs. This means they get their energy from two distinct sources: photosynthesis and active ingestion.

The zooxanthellae living in their tissues are tiny dinoflagellates. They act like internal solar panels, providing the coral with sugars and carbohydrates through photosynthesis.

However, sugar alone isn’t enough to build a complex skeleton or repair tissue. Just like we can’t survive on candy alone, corals need proteins, fats, and minerals from external sources.

So, apart from the zooxanthellae how else do corals feed? They do it by becoming active predators, filtering the water column for microscopic life and organic particles.

The Mechanics of Active Hunting: Nematocysts and Tentacles

When the lights go down, many corals transform. You might see long, clear tentacles emerge from what looked like a smooth surface during the day—these are feeding tentacles.

At the tip of these tentacles are specialized cells called nematocysts. These are essentially microscopic harpoons that can sting and paralyze tiny prey.

When a piece of zooplankton or a stray mysis shrimp touches the tentacle, the coral fires these cells. The prey is then pulled toward the central mouth of the polyp.

This predatory behavior is most visible in Large Polyp Stony (LPS) corals like Acanthophyllia or Scolymia. Watching them “fold” over a piece of food is one of the coolest sights in the hobby!

Apart From the Zooxanthellae How Else Do Corals Feed?

If we look closely at the biological processes, we find that corals are incredibly opportunistic. They don’t just wait for a big shrimp to swim by; they are constantly absorbing nutrients.

1. Capturing Zooplankton

Zooplankton consists of tiny animals like copepods, amphipods, and rotifers. In the wild, these emerge from the reef at night in massive clouds.

Corals use their tentacles to pluck these organisms from the current. This provides the essential nitrogen and phosphorus required for DNA replication and tissue growth.

In our home aquariums, we often supplement this by adding live or frozen copepods. It is a fantastic way to mimic the natural reef environment.

2. Absorbing Dissolved Organic Matter (DOM)

This is a “hidden” feeding method that many beginners overlook. Corals can actually absorb nutrients directly through their skin (the epidermis).

DOM includes things like amino acids, sugars, and organic acids dissolved in the water. This is why dosing amino acids has become so popular in the SPS (Small Polyp Stony) coral community.

Even without tentacles, a coral can “drink” in the nutrients it needs to build its colorful pigments. It is a highly efficient way for them to supplement their diet.

3. Collecting Particulate Organic Matter (POM)

You might have heard the term “marine snow.” This refers to a mix of dead organic material, bacteria, and waste that drifts through the ocean.

Corals produce a layer of mucus that acts like a sticky spiderweb. As POM drifts by, it gets stuck in this mucus.

The coral then uses tiny hair-like structures called cilia to move the mucus—and the trapped food—directly into its mouth. It’s a brilliant way to recycle waste into energy!

Feeding Different Types of Corals

Not all corals eat the same way. Depending on what you have in your Aquifarm setup, you may need to adjust your strategy.

Small Polyp Stony (SPS) Corals

SPS corals like Acropora or Montipora have very tiny mouths. They cannot eat large chunks of frozen food.

For these, you should focus on phytoplankton and fine powder foods. They rely heavily on their zooxanthellae, but they truly thrive when given “dust-sized” particles.

Don’t be afraid to use a liquid coral food. These products stay suspended in the water longer, giving the tiny polyps more time to catch them.

Large Polyp Stony (LPS) Corals

LPS corals are the “big eaters” of the reef. Corals like Euphyllia (Torches and Hammers) or Lobophyllia have huge appetites.

They can easily consume mysis shrimp, brine shrimp, or even small pieces of chopped seafood. Target feeding these corals once or twice a week can lead to massive growth.

Pro Tip: Feed your LPS corals about 30 minutes after the lights go out. This is when their natural feeding response is strongest!

Soft Corals and Octocorals

Soft corals like Leathers, Zoanthids, and Xenia are often the most efficient at absorbing DOM. Some, like Xenia, are actually thought to rely almost entirely on absorption and photosynthesis.

Gorgonians, on the other hand, are expert filter feeders. They need a constant flow of fine particles to stay healthy and extended.

The Role of Amino Acids in Coral Health

We cannot talk about how corals feed without mentioning amino acids. These are the building blocks of protein.

When we ask, apart from the zooxanthellae how else do corals feed, amino acid uptake is a primary answer for high-end reefers.

By dosing aminos, you are giving the coral the tools it needs to repair tissue and build skeleton without them having to exert energy hunting.

It’s like giving your corals a protein shake. You will often notice better “polyp extension” almost immediately after dosing.

Mastering Feeding Techniques: Target vs. Broadcast

How you deliver the food is just as important as what you feed. There are two main schools of thought in the hobby.

Broadcast Feeding

This involves pouring the food into a high-flow area of the tank and letting the pumps distribute it.

• Pros: It feeds everything at once, including the “cleanup crew” (snails and crabs).
• Cons: It can lead to nutrient spikes if you overfeed, as a lot of food ends up in the filter socks.

Target Feeding

This is a more precise method. Using a turkey baster or a dedicated “feeding tool,” you gently puff food directly onto the coral’s tentacles.

• Pros: Very little waste and ensures the coral actually gets the meal.
• Cons: It is time-consuming, especially if you have a large reef with dozens of corals.

I personally recommend a hybrid approach. Broadcast a little bit of powder to “wake up” the corals, then target feed the ones that need an extra boost.

The Risks of Overfeeding Your Reef

While it is exciting to watch your corals eat, moderation is key. In a closed aquarium system, “leftover” food becomes a problem.

If you feed too much, your nitrates and phosphates will skyrocket. This can lead to hair algae outbreaks or “browning out” of your precious corals.

Always monitor your water parameters. If you see phosphates rising, dial back the feeding frequency.

Remember, a hungry coral is better than a dead coral caused by poor water quality. Balance is the secret to a successful Aquifarm.

Why Flow Matters for Feeding

You might have the best food in the world, but if your water flow is wrong, your corals will starve.

Corals depend on current to bring food to them. In the wild, the ocean is constantly moving.

In your tank, you want random, turbulent flow. This prevents “dead spots” where food just settles on the sand and rots.

Good flow also helps the coral shed its mucus net once it has finished eating, keeping the polyp clean and healthy.

Identifying If Your Corals Are Hungry

How do you know if your feeding routine is working? Corals are very vocal through their appearance.

Signs of a well-fed coral:

• Great Polyp Extension: The tentacles are out and “reaching” for the water.
• Vibrant Color: They aren’t pale or translucent.
• Growth Tips: You see white or light-colored edges on SPS, indicating new skeleton.

Signs of a hungry coral:

• Tissue Recession: The flesh starts pulling away from the base.
• Paling: The coral looks “bleached” even if your lights aren’t too bright.
• Slow Growth: The coral looks exactly the same as it did six months ago.

If you notice these negative signs, revisit the question: apart from the zooxanthellae how else do corals feed? It might be time to start a target-feeding regimen.

FAQs About Coral Feeding

How often should I feed my corals?

For most hobbyists, 2-3 times a week is plenty. If you have a very “clean” system with low nutrients, you might feed daily.

Can corals survive on light alone?

Some can, but they won’t thrive. They will often grow much slower and be more prone to disease or stress without supplemental feeding.

Do I need to turn off my protein skimmer when feeding?

Yes! It is a good idea to turn off the skimmer for 30-60 minutes. This prevents the skimmer from immediately removing the expensive food you just added.

What is the best time of day to feed?

Most corals are nocturnal hunters. Feeding in the evening or shortly after the lights go out usually yields the best results.

Can I feed my corals “human” food?

You can use fresh, raw seafood like shrimp or scallops, provided they are finely minced and have no additives or preservatives.

Conclusion: Achieving a Thriving Reef

Understanding that corals are more than just “living rocks” is the first step toward mastery. While light provides the “fuel,” external feeding provides the “building blocks.”

By answering the question, apart from the zooxanthellae how else do corals feed, we unlock the potential for massive growth and stunning coloration. Whether you choose to dose amino acids or target-feed mysis shrimp, your corals will thank you.

Keep a close eye on your water parameters, provide plenty of flow, and don’t be afraid to experiment with different food types. Every reef is unique!

Happy reefing, and remember that a well-fed coral is a happy coral. If you have any questions about specific species, feel free to reach out to us here at Aquifarm!