What Does A Coral Eat – The Ultimate Guide To Healthy Reef Nutrition

Keeping a vibrant reef tank is one of the most rewarding challenges in the aquarium hobby, but it often comes with a steep learning curve. You’ve likely spent hours perfecting your water chemistry and lighting, yet you might still find yourself asking, what does a coral eat to truly thrive?

If you feel a bit overwhelmed by the conflicting advice online, don’t worry—this guide is designed to simplify everything for you. Whether you are a beginner with your first mushroom coral or an intermediate keeper branching into “SPS,” I will walk you through the fascinating world of coral nutrition.

In this article, we will explore the dual-nature of coral feeding, the best types of prepared foods, and the practical techniques you can use to ensure your reef stays healthy and colorful. Let’s dive into the microscopic world of coral polyps!

Understanding what does a coral eat: The Dual Nutrition Strategy

To understand how to feed your reef, you first need to realize that corals are mixotrophs. This means they have two primary ways of getting the energy they need to grow and build their calcium carbonate skeletons.

The first method is “internal,” utilizing a symbiotic relationship with tiny algae. The second method is “external,” where the coral actively captures food from the water column, much like a tiny predator.

In the wild, corals have evolved to be highly efficient at both. In our home aquariums, we must replicate these natural processes to prevent our corals from starving or losing their vibrant pigments.

The Role of Zooxanthellae and Light

Most corals house microscopic algae called zooxanthellae within their tissues. These algae perform photosynthesis, converting light energy into sugars and amino acids that the coral consumes.

This is why high-quality LED or T5 lighting is so critical for reef tanks. Without enough “PAR” (Photosynthetically Active Radiation), the zooxanthellae cannot produce enough food for their host.

However, light alone is rarely enough for long-term health. While it provides the “calories,” corals still need proteins and minerals from external sources to repair tissue and reproduce.

The Anatomy of a Feeding Polyp

Every coral is made up of individual or colonial polyps. Each polyp is essentially a tiny mouth surrounded by stinging tentacles called nematocysts.

When a piece of food touches these tentacles, the coral “stings” it and pulls it into the central mouth. This is the most direct answer to what does a coral eat—they eat small organisms found in the water.

The Different Types of Coral Food

When you walk into a local fish store, the shelves are lined with various powders, liquids, and frozen cubes. Choosing the right one depends on the specific species you keep and their polyp size.

Not all corals can eat the same things. A Large Polyp Stony (LPS) coral has a massive mouth, while a Small Polyp Stony (SPS) coral relies on catching microscopic particles.

Phytoplankton: The Base of the Food Chain

Phytoplankton consists of microscopic plants and algae. While many corals do not eat phytoplankton directly, it is essential for the overall health of your “micro-fauna.”

Adding phytoplankton feeds the copepods, rotifers, and feather dusters in your tank. These organisms then become a natural, live food source for your corals.

It is a great way to boost the biodiversity of your aquarium. I always recommend adding a small dose of live phytoplankton a few times a week to keep the ecosystem balanced.

Zooplankton and Micro-Foods

Zooplankton are tiny animals, such as copepods, mysis shrimp, and brine shrimp. These are the “meat” of the coral diet and provide the protein necessary for growth.

For corals with small polyps, you can use specialized powdered foods like Reef Roids or Benepellet. These powders mimic the size of natural zooplankton found on the reef.

If you have corals with larger mouths, such as Acans or Scolymia, they will happily devour whole mysis shrimp or small pieces of chopped seafood.

Amino Acids and Dissolved Organics

Corals also “drink” their food by absorbing dissolved organic matter directly from the water. Amino acids are the building blocks of protein and are vital for coral coloration.

Many modern reefers use liquid amino acid supplements to help corals recover from stress or to enhance their natural “fluorescence.”

Just be careful not to overdo it! Adding too much liquid food can lead to a spike in nitrates and phosphates, which might trigger an unwanted algae bloom in your display tank.

How to Feed Your Corals: Techniques for Success

Knowing what does a coral eat is only half the battle; you also need to know how to deliver that food effectively without polluting your water.

There are two primary methods used by hobbyists: broadcast feeding and target feeding. Each has its pros and cons depending on your tank setup.

The Broadcast Feeding Method

Broadcast feeding involves mixing your coral food with some tank water and pouring it into the flow of your powerheads. This distributes the particles throughout the entire aquarium.

This is the easiest method and is perfect for tanks with many small-polyp corals or soft corals like “Gorgonians.” It ensures that every polyp has a chance to catch something.

The downside is that much of the food may end up in your filter socks or protein skimmer. To prevent waste, I suggest turning off your return pump but leaving your internal powerheads on low.

The Target Feeding Method

Target feeding is a much more precise way to ensure your corals are getting their fill. You use a “turkey baster” or a specialized “feeding tool” to puff food directly onto the coral’s polyps.

This is highly effective for LPS corals like Torch corals, Brain corals, and Elegance corals. Watching a coral grab a piece of shrimp and pull it into its mouth is one of the coolest sights in the hobby!

Target feeding reduces waste because you control exactly where the food goes. It also allows you to give extra attention to corals that might be struggling or growing slowly.

When is the Best Time to Feed?

Most corals are nocturnal feeders. In the wild, they extend their tentacles at night when the risk of being picked at by fish is lower.

You can “trick” your corals into feeding during the day by adding a tiny amount of food to the water to trigger their feeding response. Within minutes, you’ll see their tentacles extend.

However, if you want to see the most natural behavior, try feeding about 30 minutes after your lights go out. Use a red flashlight so you don’t startle the fish!

Specific Needs by Coral Type

Not all corals have the same appetite. To be a successful aquarist, you should tailor your feeding routine to the specific “residents” of your reef.

Soft Corals (Leathers, Mushrooms, Zoanthids)

Soft corals are generally very hardy and get most of what they need from light and dissolved organics in the water. They are the “easy keepers” of the reef world.

Zoanthids, however, do appreciate small particulate foods. What does a coral eat if it’s a softie? Mostly “detritus” and very fine micro-plankton.

If your tank is “too clean,” these corals might actually look shriveled. They prefer a bit of “dirtier” water with measurable nitrates and phosphates.

LPS Corals (Large Polyp Stony)

LPS corals are the hungriest group. Because they have large, fleshy bodies and big mouths, they require regular “meaty” meals to stay inflated and healthy.

I recommend target feeding LPS corals 1–2 times per week. They love mysis shrimp, krill, and specialized LPS pellets.

If you notice your LPS coral is losing its color or the skeleton is starting to show, it’s a clear sign it needs more direct feeding and perhaps more stable alkalinity.

SPS Corals (Small Polyp Stony)

SPS corals, like Acropora and Montipora, are the most demanding. Their polyps are tiny, so they cannot eat large pieces of food.

They rely heavily on high-quality light and micro-particulate food. Amino acid dosing is particularly beneficial for SPS, as it helps them maintain their bright, “neon” colors.

Strong water flow is also essential here. The flow brings the food to the polyps and carries away waste products, acting as a conveyor belt for their nutrition.

Maintaining Water Quality While Feeding

The biggest mistake beginners make is overfeeding. While we want to answer the question of what does a coral eat, we must also remember that “uneaten food equals pollution.”

Excess food breaks down into ammonia, then nitrites, and finally nitrates and phosphates. High levels of these can stunt coral growth and lead to “nuisance algae” like hair algae or cyanobacteria.

Monitoring Your Nutrients

Invest in high-quality test kits for Nitrate (NO3) and Phosphate (PO4). Aim for a “sweet spot” where your corals have enough food, but the algae doesn’t take over.

A common target for a mixed reef is Nitrates at 5–10 ppm and Phosphates at 0.03–0.10 ppm. If your levels are at zero, your corals might actually be starving!

The Importance of Filtration

If you plan on feeding heavily to achieve fast growth, you need a robust filtration system. A high-quality protein skimmer is your best friend in a reef tank.

The skimmer removes organic waste before it has a chance to break down. This allows you to feed your corals the proteins they need while keeping the water crystal clear.

Don’t forget regular water changes! Changing 10–15% of your water every two weeks helps replenish trace elements and exports excess nutrients that the skimmer might miss.

FAQ: Common Questions About Coral Feeding

Do corals need to be fed every day?

No, most corals do not need daily feeding. In a typical aquarium with fish, corals will catch leftover fish food and fish waste. Direct feeding 1–3 times a week is usually plenty.

Can corals survive on light alone?

Some corals, like certain “Leathers” or “Xenia,” can survive primarily on light and dissolved nutrients. However, almost all corals will grow faster and look better with supplemental feeding.

What happens if I overfeed my corals?

Overfeeding leads to poor water quality. You might see an explosion of algae, a decline in pH, or even “tissue necrosis” in sensitive corals due to high phosphate levels.

Why won’t my coral open its mouth to eat?

If a coral isn’t showing a feeding response, it might be stressed. Check your salinity, temperature, and alkalinity. Also, ensure no fish are nipping at it, causing it to stay retracted.

Do I need to feed “filter-feeding” corals differently?

Yes! Non-photosynthetic (NPS) corals, like Sun Corals or Sea Fans, do not have zooxanthellae. They require constant, heavy feeding of micro-foods because they cannot get energy from light.

Conclusion: Finding the Right Balance for Your Reef

Understanding what does a coral eat is a journey of observation and patience. Every reef tank is a unique ecosystem, and what works for one hobbyist might not work for another.

Start slowly by introducing one or two types of high-quality coral food. Observe how your polyps react—do they extend their tentacles? Do they show better color after a few weeks?

The goal is to provide a diverse diet that mimics the rich “plankton soup” of the ocean while maintaining the pristine water quality that corals demand.

Keep a close eye on your nutrient levels, don’t be afraid to experiment with target feeding, and most importantly, enjoy the process! With the right nutrition, your aquarium will soon be a thriving, underwater masterpiece.

Happy reefing, and remember that a well-fed coral is a happy, growing coral!