Coral Feeding

Many reef keepers operate under the assumption that corals get everything they need from light and the dissolved nutrients in their water. For photosynthetic corals, light does provide the majority of their energy through the symbiotic zooxanthellae algae living in their tissues. But light alone does not supply the amino acids, fatty acids, and trace nutrients that corals need for tissue growth, skeletal development, and the kind of vibrant coloration that makes a reef tank worth staring at. Active feeding bridges that gap, and the difference between a reef that is merely surviving and one that is genuinely thriving often comes down to whether the corals are being fed.

Coral feeding is where reef keeping shifts from water chemistry management into something closer to animal husbandry. Corals are animals, not plants, and they have evolved to capture and consume food from the water around them. In the wild, ocean currents deliver a constant stream of phytoplankton, zooplankton, dissolved organic matter, and particulate nutrients that corals intercept with their polyps. Your aquarium does not have ocean currents delivering wild plankton, which means you are responsible for replicating that nutritional input through deliberate feeding.

The reluctance many reef keepers feel about coral feeding usually stems from legitimate concerns about nutrient loading. Every bit of food that enters a reef tank adds nitrogen and phosphorus to the system, and excess nutrients fuel nuisance algae that compete with corals for space and light. This concern is valid but manageable. The solution is not to avoid feeding altogether - it is to feed appropriately using techniques that deliver nutrition to the corals while minimizing waste that enters the water column. Experienced reef keepers who master this balance consistently produce healthier, faster-growing coral colonies than those who rely on light alone.

This topic applies to anyone keeping corals, from soft coral beginners with a small mixed reef to advanced hobbyists maintaining demanding SPS colonies. The specific feeding requirements vary by coral type, but the fundamental principles of when, how, and why to feed apply across the board. Even photosynthetic corals that theoretically survive on light alone show measurably better growth rates, coloration, and resilience when supplemental feeding is provided. Non-photosynthetic corals like sun corals and tubastrea are entirely dependent on active feeding and will starve without it.

This article covers the practical side of coral feeding - the techniques, timing, and methods that get nutrition into your corals effectively. You will learn how to prepare for a feeding session, the difference between target feeding and broadcast feeding, how the light cycle affects coral feeding response, which corals need the most attention, and how to feed without triggering the water quality problems that give coral feeding its undeserved bad reputation.

Corals obtain nutrition through multiple pathways, and understanding these pathways helps you make smarter feeding decisions. Photosynthesis through zooxanthellae provides the bulk of energy for most reef corals, primarily in the form of simple sugars. But sugars are fuel, not building materials. The amino acids needed for tissue growth, the fatty acids needed for cell membranes, and the calcium and trace minerals needed for skeletal construction must come from captured food or absorption from the water column. Feeding supplements what light provides, turning bare-minimum survival into active growth.

The nutritional value of coral food depends heavily on particle size and composition. Corals capture food using their polyps, and polyp size varies enormously between species. Large polyp stony corals like acanthastrea, lobophyllia, and favia can capture and consume relatively large food particles including mysis shrimp, brine shrimp, and even small pellets. Small polyp stony corals like acropora, montipora, and stylophora have tiny polyps that can only capture food in the range of five to fifty microns - essentially phytoplankton and bacterioplankton-sized particles. Feeding the wrong particle size to a coral is like offering a steak to an animal that can only eat soup. The food is there but the coral cannot physically consume it.

Amino acids are arguably the most impactful nutrient class for coral health and appearance. Corals use amino acids to build the proteins that form their tissue, produce mucus for protection and food capture, and synthesize the fluorescent pigments responsible for the stunning colors reef keepers prize. Corals that receive adequate amino acids through feeding display deeper, more intense coloration than corals relying solely on photosynthesis. This is why many experienced reef keepers consider amino acid supplementation - whether through direct dosing or through feeding amino acid-rich foods - to be one of the highest-impact improvements they can make to their coral care routine.

Fatty acids, particularly the highly unsaturated varieties found in marine plankton, serve critical roles in coral cellular health. These fats maintain the integrity of cell membranes, support the health of the zooxanthellae living within coral tissue, and provide energy reserves that corals draw on during stressful events like temperature spikes or shipping. Corals with adequate fatty acid intake recover faster from stress and are more resistant to bleaching events. Marine-sourced coral foods naturally contain these fatty acids, which is one reason marine-specific products outperform generic supplements for coral nutrition.

Dissolved organic matter represents a feeding pathway that many reef keepers overlook. Corals absorb dissolved amino acids, fatty acids, and other organic compounds directly from the water through their tissue surfaces. In a well-stocked reef tank with fish, the fish waste and uneaten fish food actually contribute dissolved organics that corals can utilize. This is one reason why fish-only tanks that are later converted to reef tanks sometimes see initial coral success even before deliberate coral feeding begins. The fish are inadvertently feeding the corals through the dissolved nutrients they generate. However, relying entirely on fish-generated nutrients is inconsistent and often provides the wrong nutrient ratios for optimal coral health.

Target feeding delivers food directly to individual coral colonies using a syringe, turkey baster, or dedicated coral feeding pipette. This is the most efficient method because it minimizes food waste in the water column while ensuring each coral actually receives nutrition. The technique involves drawing up a small amount of prepared food, positioning the syringe tip a few inches from the coral's polyps, and gently releasing the food so it drifts onto the coral's surface. Most corals respond to food contact by extending their polyps and beginning to capture particles within seconds. Target feeding works best for large polyp corals that can handle visible food particles and for non-photosynthetic corals that depend entirely on captured food.

Broadcast feeding disperses food throughout the entire water column so that all corals have the opportunity to capture particles as the flow carries them past. This method is better suited to small polyp corals that cannot be individually target-fed because their polyps are too small to see individual feeding responses. Turn off your return pump and powerheads for ten to fifteen minutes during broadcast feeding to allow food particles to settle and remain in contact with coral surfaces longer. Without this flow reduction, most of the food passes through the tank too quickly for corals to capture it and ends up in your overflow or filter sock, wasting food while adding nutrients to the water for no benefit.

Timing your feeding sessions around the light cycle significantly affects coral feeding response. Many corals extend their feeding polyps most actively after the lights go out or during the transition from full light to darkness. This is because in the wild, zooplankton migrates upward from deeper water as daylight fades, and corals have evolved to feed most aggressively during this period. Feeding during the last hour of your light cycle or within the first hour after lights-off typically produces the best polyp extension and food capture rates. Some reef keepers dedicate a blue-light-only period specifically for coral feeding, which stimulates polyp extension while allowing them to observe the feeding response.

Feeding frequency depends on your coral types and your willingness to manage the resulting nutrient load. Most mixed reef tanks benefit from feeding two to three times per week, which provides meaningful nutrition without overwhelming your filtration and export systems. Tanks dominated by non-photosynthetic corals may need daily feeding because these corals have no photosynthetic backup and depend entirely on captured food. Heavily stocked SPS tanks where nutrient control is critical may do better with less frequent but more carefully targeted feedings. Start with twice per week and adjust based on coral response and your ability to maintain stable water parameters.

Preparing for a feeding session takes a few minutes but makes the process cleaner and more effective. Thaw any frozen food in a small cup of tank water and strain out the excess liquid before feeding. Mix powdered or liquid coral foods according to the manufacturer's directions - more concentrated is not better and just adds unnecessary nutrients to your water. Have your feeding tools ready and know which corals you plan to target feed before you start. If you broadcast feed, have your powerheads on a timer or be ready to turn them off manually. The more organized your feeding routine, the more food actually reaches corals and the less ends up as wasted nutrient input.

Large polyp stony corals are the most rewarding to feed because their feeding response is dramatic and visible. Species like acanthastrea, lobophyllia, blastomussa, and open brain corals extend large, fleshy polyps that actively grab food and draw it into their mouths. These corals accept a wide range of foods including mysis shrimp, finely chopped raw shrimp, reef-specific pellets, and liquid coral foods. Target feeding LPS is straightforward - place the food on or near the polyp and watch it respond. Feed LPS one to three times per week for best growth and coloration, though many will survive with less frequent feeding.

Small polyp stony corals have a more complex relationship with feeding because their tiny polyps limit the particle sizes they can capture. SPS corals like acropora, montipora, and pocillopora primarily rely on photosynthesis but measurably benefit from feeding with appropriately sized foods. Phytoplankton, bacterioplankton-sized foods, and amino acid supplements in the five to fifty micron range are what SPS corals can actually utilize. Broadcast feeding during low-flow periods is the practical approach for SPS because target feeding individual polyps is not realistic. The growth rate and coloration improvements from regular SPS feeding are well documented by reef keepers who track their colonies over time.

Soft corals including mushrooms, zoanthids, leather corals, and xenia have varying feeding requirements that are often underestimated. Many soft corals are highly photosynthetic and survive without direct feeding, but they respond positively to periodic supplementation with phytoplankton or liquid coral foods. Mushroom corals in particular are surprisingly effective feeders that will capture and consume mysis shrimp and other meaty foods when offered directly. Zoanthids benefit from broadcast feeding with fine particulate foods. The feeding response in soft corals is generally less dramatic than in LPS, but the long-term growth and health benefits are real.

Non-photosynthetic corals including sun corals, tubastrea, black sun corals, and dendronephthya are the most demanding feeders in the reef hobby because they have no zooxanthellae and cannot derive any energy from light. These corals must be target-fed regularly - often daily for newly acquired specimens and at least every other day once established. They typically feed best after lights-out when their polyps are fully extended. Mysis shrimp, cyclops, and enriched brine shrimp are all effective food choices. Keeping non-photosynthetic corals healthy requires a genuine commitment to consistent feeding that many reef keepers underestimate before acquiring them.

Filter-feeding invertebrates that often coexist with corals in reef tanks have their own feeding considerations that overlap with coral feeding. Feather duster worms, sponges, clams, and certain anemones all capture food from the water column. When you broadcast feed for corals, these organisms benefit as well. Clams in particular need phytoplankton for their nutritional needs, and incorporating phytoplankton into your coral feeding routine supports clam health simultaneously. The key is recognizing that your reef tank's feeding needs extend beyond just the corals to encompass the entire community of filter-feeding organisms sharing that space.

Corals that are not receiving adequate nutrition from feeding or photosynthesis display a gradual loss of tissue color that many reef keepers initially mistake for lighting problems. The coral's color pales over weeks, shifting from deep greens, purples, or reds toward lighter, washed-out versions of those colors. In SPS corals, inadequate nutrition combined with high light can produce the bleached-looking pale appearance that some beginners actually find attractive without realizing the coral is struggling. Tissue that looks translucent or allows the white skeleton to show through is a coral in nutritional trouble, not a coral displaying a desirable color morph.

Reduced polyp extension is a direct behavioral indicator that feeding is either inadequate or poorly timed. Healthy, well-fed corals extend their polyps regularly, particularly during low-light periods. Corals that keep their polyps retracted most of the time or only extend them weakly and briefly may not be finding enough food in the water column to justify the energy expenditure of polyp extension. If you notice that corals which used to extend beautifully have become increasingly retracted, evaluating and improving your feeding routine should be among the first responses before investigating other possible causes.

Slow growth or no visible growth over months in established corals that should be actively growing points toward nutritional limitation. Photosynthesis alone provides enough energy for basic survival in most reef corals, but active growth - laying down new skeleton, expanding tissue, and producing new polyps - demands the amino acids, fatty acids, and trace nutrients that only feeding provides. Reef keepers who begin a consistent feeding program after months of light-only care frequently report a noticeable acceleration in coral growth within four to six weeks, confirming that the previous growth rate was nutritionally limited.

Tissue recession, where the living tissue of a coral slowly retreats from its outer edges exposing bare skeleton, can indicate long-term nutritional deficiency among other possible causes. This is particularly common in LPS corals that are capable of feeding but are not receiving food. The coral essentially cannot maintain all of its tissue on photosynthesis alone and begins sacrificing peripheral tissue to sustain the core colony. While tissue recession has multiple possible causes including water chemistry problems and aggression from neighboring corals, nutritional status should always be evaluated as part of the diagnostic process.

On the opposite end, overfeeding produces its own recognizable problems. Elevated nitrate and phosphate levels that rise faster than your export systems can control indicate you are adding more food than your corals and filtration can process. Nuisance algae growth that outpaces your cleanup crew, cyano bacteria blooms on the sandbed, and film algae on the glass appearing faster than usual are all signs that the nutrient load from feeding exceeds the tank's capacity to utilize and export it. The solution is not to stop feeding but to reduce frequency or volume, improve your protein skimmer performance, and possibly add additional nutrient export methods like media reactors or refugium macroalgae.

Invest in a quality set of coral feeding tools and you will find that feeding becomes faster, cleaner, and more effective. A set of long coral feeding syringes in different sizes - a small one for precise target feeding and a larger one for mixing and dispensing broadcast food - makes the physical process much easier than improvising with kitchen tools. Dedicated coral feeding pipettes with flexible tips let you reach corals in awkward positions without disturbing their neighbors. These tools cost very little and last for years.

Create a feeding schedule that you can actually maintain rather than an ambitious plan that falls apart after two weeks. Consistency matters more than frequency with coral feeding. Two reliable feedings per week will produce better long-term results than daily feeding that happens for a month and then stops because it felt like too much work. Write your feeding days on the calendar, set a phone reminder, or tie it to another routine you already do consistently. The corals do not care what day of the week they eat - they care that it happens regularly.

Run your protein skimmer on a schedule that accounts for feeding. Many reef keepers turn their skimmer off during feeding and for one to two hours afterward to prevent it from removing the food before corals can capture it. This is particularly important for broadcast feeding where fine particles are easily pulled into the skimmer intake. After the feeding window, turn the skimmer back on to process any excess nutrients. Some advanced setups use a timer to automate this cycle.

Track your coral response to feeding over time rather than expecting immediate visible results. Take photos of your corals monthly under consistent lighting and compare them over a three to six month period after beginning a feeding program. Growth measurements using a simple ruler next to benchmark colonies tell you whether your feeding approach is producing results. This data helps you fine-tune your routine - if corals are responding well, maintain the program. If growth and color have not improved, you may need to adjust food types, particle sizes, or feeding frequency to better match what your specific coral community needs.