how to prepare frozen food correctly, which corals need target feeding
and how to do it, and the direct connection between feeding and water quality.
Every gram of food added to the tank is eventually a unit of ammonia,
nitrate, and phosphate that the filtration system must export. Feed
more than the system can process and nutrients accumulate, gradually,
invisibly, until algae appears or coral color fades. Feed too little
and fish lose condition, immune systems weaken, and corals that depend
on direct feeding fail to grow.
The goal isn’t minimum feeding, it’s calibrated feeding. The right
food, in the right amount, prepared correctly, at the right frequency
for the specific livestock in the tank. This guide covers all of it.
Fish Food Types, What Each Does and When to Use It
| Food Type | Nutritional Value | Best For | Drawbacks | Verdict |
|---|---|---|---|---|
| Frozen mysis shrimp | Excellent, high protein, natural prey item, triggers strong feeding response in most marine fish | Primary food source for most reef fish; works for nearly every species | Thaw liquid is high in phosphate, must be strained before adding to tank | ✅ Best all-around primary food |
| Frozen brine shrimp | Low, high water content, poor protein-to-bulk ratio; often called “junk food” for marine fish | Getting picky fish to start eating; mixing with more nutritious food to improve acceptance | Poor nutritional density; fish fill up without getting adequate protein; should not be a primary food | ⚠️ Use as supplement only, not as a primary food |
| Frozen enriched brine shrimp | Better than standard brine, enriched with vitamins and fatty acids (Spirulina, HUFA) | Picky fish; mixing with mysis for variety; good for herbivorous species | Still lower nutritional density than mysis; more expensive than standard brine | ✅ Good supplement, still not a primary food replacement |
| Frozen Rotifers / Copepods | Excellent for appropriate species, natural prey size and composition | Mandarin dragonets, small wrasses, flasher wrasses, small gobies; supplement for filter-feeding corals and clams | Expensive; most fish are too large to find them useful; primarily for specific species or coral feeding | ✅ Essential for mandarins and nano-prey species; coral feeding supplement |
| High-quality pellet food (New Life Spectrum, Hikari, Reef Nutrition) | Excellent if brand is reputable, complete diet formulated for marine fish; good protein and vitamin profile | Daily feeding; excellent as a base food for omnivorous reef fish; convenient and consistent nutrient delivery | Some fish are reluctant to accept initially, particularly if wild-caught; less effective than frozen for picky eaters | ✅ Excellent convenience food, alternate with frozen for variety |
| Flake food | Variable, quality ranges enormously; budget flakes are nutritionally poor | Surface feeding fish; small fish; secondary supplement | Dissolves quickly and releases nutrients into the water faster than pellets or frozen; poor choice for tanks watching nutrients closely | ⚠️ Use quality brands only; inferior to pellets and frozen for most applications |
| Nori / dried seaweed sheets | Excellent for herbivores, essential dietary component for tangs, rabbitfish, some blennies | Any tang or rabbitfish in the tank, non-negotiable for long-term health | Uneaten pieces release nutrients rapidly; clip to a feeding clip and remove uneaten portions after 2–3 hours | ✅ Required for any tang; clip in tank daily or every other day |
| Live copepods | Excellent, live prey triggers the strongest natural feeding response; ideal for mandarin dragonets and other obligate pod eaters | Mandarin dragonets, scooter blennies, leopard wrasses; refugium seeding | Expensive; consumed quickly without a refugium to sustain population; requires ongoing purchase or refugium cultivation | ✅ Essential for mandarins; supplement for predatory nano-fish |
How to Prepare Frozen Food, The Step Most Beginners Skip
Frozen food preparation is the single most impactful feeding habit
change most beginners can make. The liquid that frozen mysis and
brine shrimp are packed in, the thaw liquid, contains a high
concentration of phosphate, dissolved proteins, and preserved packing
compounds. Adding this liquid to the tank with every feeding is one
of the most consistent phosphate sources in a reef tank that isn’t
being managed correctly.
The Correct Frozen Food Preparation Process
- Cut the portion size before thawing. A frozen cube
of mysis is typically more food than a 25-gallon reef tank needs in
one feeding. Cut the cube in half or quarters with a knife while
still frozen. Use only what the tank needs; store the remainder in
the freezer. - Thaw in a small cup of tank water. Place the frozen
portion in a shot glass or small cup and add a small amount of tank
water. Allow to thaw for 3–5 minutes, don’t use warm water to rush
thawing, it degrades nutritional value. - Strain the thaw liquid. Hold a fine mesh strainer
(a dedicated brine shrimp net or a fine kitchen strainer) over the
cup and pour the thawed food through it. The food stays in the
strainer; the liquid drains away. Rinse the strained food briefly
with RODI water to remove any remaining liquid. - Add the strained food to the tank using a pipette,
turkey baster, or feeding stick to direct it toward fish or specific
coral placement areas. Don’t dump it all in one spot, distribute
across the water column so all fish have access.
This process takes 2–3 minutes and removes a meaningful phosphate
load from the tank with every feeding. For a tank feeding twice daily,
correctly strained frozen food over a month produces measurably lower
phosphate readings than the same feeding volume with thaw liquid
included. It’s the easiest and cheapest water quality improvement
available.
How Much and How Often, by Fish Type
The universal rule: feed only what fish consume within 2
minutes per feeding session. Food that sinks to the sandbed
and isn’t consumed within a few minutes begins decomposing immediately.
2 minutes is enough time for active reef fish to find and eat
all food in their territory. If food is still drifting after 2 minutes,
the portion was too large.
Feeding Frequency by Fish Category
| Fish Category | Examples | Feeding Frequency | Primary Food | Notes |
|---|---|---|---|---|
| Omnivorous reef fish | Ocellaris and percula clownfish, royal gramma, firefish goby, dartfish | 2–3 small feedings per day | Frozen mysis + quality pellets alternated | The standard feeding regime for most beginner community fish. Small and frequent beats large and infrequent for both fish health and water quality. |
| Herbivorous / algae-grazing fish | Tang species (yellow, blue, sailfin), lawnmower blenny, rabbitfish | 2 feedings daily + nori available continuously | Nori clipped in tank daily; mysis supplemented 2× daily | Tangs and rabbitfish graze continuously in the wild, a single daily feeding is insufficient. Clip nori to a feeding clip and leave it for 2–3 hours; remove uneaten portions. Without adequate algae in the diet, tangs develop nutritional deficiencies over months. |
| Carnivorous fish | Hawkfish, larger wrasses, lionfish (advanced) | Once daily; some species every other day | Frozen mysis, silversides, larger prey items appropriate to mouth size | Carnivores have slower digestion than omnivores. Overfeeding a hawkfish produces significant waste. Watch body condition, a slightly rounded abdomen is correct; bloated is overfeeding. |
| Gobies (substrate-associated) | Watchman goby, clown goby, neon goby | 2–3 small feedings per day | Frozen mysis; some species accept pellets | Gobies often miss food distributed across the water column, they’re not active water-column feeders. Use a feeding stick or pipette to deliver food near their territory on the rockwork or sandbed. Watchman gobies that aren’t being fed directly often fail to compete for food in a community tank. |
| Mandarin dragonet / scooter blenny | Synchiropus splendidus, Synchiropus ocellatus | Continuous, hunts throughout the day | Live copepods (primary); frozen copepods and rotifers (supplement for tank-trained individuals) | Mandarins are obligate pod eaters that hunt continuously. A 25-gallon tank without a refugium cannot maintain a copepod population adequate to sustain a mandarin long-term. A mandarin without a refugium copepod culture slowly starves over 3–6 months even when other fish in the tank look healthy. Not recommended for beginners without a refugium. See: Best Fish for a Beginner Reef Tank |
| Pipefish / seahorse | Advanced species, not beginner appropriate | Multiple times daily | Live mysis, live copepods | Not recommended for beginner reef tanks, require dedicated feeding regimes incompatible with most community setups. |
The Fasting Day
One day per week with no feeding is beneficial for most reef tanks.
Marine fish in the wild experience periods without food, their
digestive systems are adapted for this. A weekly fast day:
- Reduces weekly nutrient input by approximately 14%
- Encourages fish to graze algae from the rockwork, naturally supplementing their diet
- Gives the filtration system a low-input day to catch up on accumulated organics
- Does not cause any harm to healthy, well-fed fish
Skip the fasting day for tanks with mandarins, seahorses, pipefish,
or any fish that’s underweight or newly introduced.
Feeding and Water Quality, The Direct Connection
Every feeding decision has a direct water quality consequence.
Understanding this connection makes the reasoning behind the feeding
guidelines above make sense rather than feeling like arbitrary restrictions.
The Nutrient Pathway
Food enters the tank → fish eat it → fish excrete ammonia through
their gills and waste → biological filtration converts ammonia to
nitrate → nitrate accumulates until removed by water changes.
Uneaten food → sinks to sandbed → decomposes → releases ammonia
AND phosphate → same biological filtration pathway plus phosphate
accumulation that has no biological removal mechanism in the display.
Every gram of food added, whether eaten or not, eventually becomes
ammonia, nitrate, and phosphate in the water. The filtration system
and water changes are removing these compounds as they’re produced.
When the production rate exceeds the removal rate, nutrients rise.
Overfeeding is the most common reason nutrient production exceeds
removal capacity in beginner tanks, and it’s the easiest one to fix.
How Overfeeding Shows Up
| Symptom | Timeline After Overfeeding Begins | Connection to Feeding |
|---|---|---|
| Rising nitrate on weekly tests | 2–4 weeks | Direct, more food in = more ammonia processed to nitrate |
| Rising phosphate | 2–4 weeks | Direct, uneaten food and thaw liquid are primary phosphate sources |
| Green hair algae on rockwork | 4–8 weeks | Indirect, GHA is fueled by elevated nitrate and phosphate from overfeeding |
| Coral color fading toward brown | 6–12 weeks | Indirect, elevated phosphate above 0.05 ppm suppresses coral fluorescence and calcification |
| Protein skimmer working harder / darker output | 1–2 weeks | Direct, more dissolved organics from food means more skimmate produced |
| Filter floss loading faster | Immediate | Direct, food particles add to mechanical filtration load |
Diagnosing an Overfeeding Problem
If nitrate and phosphate are rising despite consistent water changes
and correct filter floss change frequency, overfeeding is the most
likely cause. Test this by reducing feeding volume by 30% for two weeks
while continuing the same water change schedule. If nitrate and phosphate
stop rising or begin falling, overfeeding was the primary driver.
If they continue rising at the same rate, look at other nutrient sources:
old filter floss, failing skimmer, tap water top-offs, or a dead animal
decomposing undetected.
See: Reef Tank Water Testing Guide
Feeding Corals, Which Need It, Which Don’t, and How to Do It
All reef corals are photosynthetic, their zooxanthellae convert
light into the majority of the energy they use for growth and calcification.
In a well-lit tank, most soft corals and many LPS corals receive
adequate energy from photosynthesis alone without direct feeding.
But “adequate” and “optimal” are different things, and direct feeding
measurably improves growth rate and tissue health in most coral species
that have the polyp structure to capture food.
Coral Feeding Requirements by Type
| Coral Type | Examples | Feeding Requirement | Best Food | Target Feeding Method |
|---|---|---|---|---|
| Mushroom corals (Discosoma, Rhodactis) | Blue mushroom, hairy mushroom, elephant ear | Low, photosynthesis is primary energy source; direct feeding is optional but improves growth | Small mysis, Reef Roids, Coral Frenzy | Reduce flow during feeding; place food directly on the disk surface; once per week is sufficient |
| Zoanthids (Zoanthus, Palythoa) | PPE zoanthids, palythoa grandis, button polyps | Low to moderate, light is primary; direct feeding accelerates growth | Rotifers, coral powder foods, Reef Roids dissolved in water column | Broadcast fine coral foods into the water column near zoanthids during low-flow periods; individual polyp target feeding is impractical at scale |
| Green Star Polyps (GSP) | Briareum asbestinum | Very low, grows rapidly on light alone; direct feeding rarely necessary | Fine particulate foods in water column | None required; GSP that’s not encrusting is a flow or light problem, not a feeding problem |
| Leather corals (Sarcophyton, Sinularia) | Toadstool leather, finger leather, colt coral | Very low, photosynthesis dominant; direct feeding provides negligible benefit | N/A | No target feeding required; focus on stable flow and light |
| LPS, large polyp feeders | Duncan coral, Goniopora (flower pot), brain corals | Moderate to high, these corals have large sweeper tentacles adapted for prey capture; direct feeding significantly improves health and growth | Frozen mysis, frozen cyclops, Reef Roids, small meaty foods | Reduce flow 10–15 minutes before feeding; use a pipette or feeding stick to place food directly onto extended tentacles; feed weekly to twice weekly |
| LPS, sweeper tentacle feeders | Hammer coral, torch coral, frogspawn, bubble coral | Moderate, sweeper tentacles capture prey; direct feeding improves growth rate; not mandatory for survival but beneficial | Frozen mysis, Reef Roids, small meaty frozen foods | Use feed mode on wavemaker to reduce flow; pipette food near (not directly at) extended sweeper tentacles; let the coral’s movement bring food to the tentacle tips; feed weekly |
| NPS (Non-Photosynthetic) corals | Sun corals (Tubastrea), carnation corals, gorgonians | Very high, no photosynthetic zooxanthellae; require direct feeding to survive | Frozen mysis, live brine, frozen cyclops, broadcast coral foods | Must be target fed every 1–2 days; not appropriate for beginner tanks, NPS corals starve in tanks without dedicated feeding regimes |
| SPS (Small Polyp Stony) corals | Acropora, Montipora, Pocillopora, Seriatopora | Low direct feeding requirement, polyps are small and most nutrition comes from light and dissolved organics in the water; target feeding has limited benefit | Fine coral foods, phytoplankton, dissolved organics | Broadcast fine foods into the water column; target feeding impractical given polyp size; focus on stable chemistry and light rather than direct feeding |
How to Target Feed Corals Correctly
- Reduce flow 10–15 minutes before feeding. Use your
wavemaker’s feed mode (most modern wavemakers have a dedicated feed
mode that pauses or significantly reduces flow for a set period).
Corals extend their feeding tentacles more fully in calmer water,
and food delivered in high flow is swept past the coral before
tentacles can respond. - Wait for full polyp extension. Only feed corals
that have their feeding tentacles extended. A closed coral won’t
capture food, it’s not in feeding mode. Target feeding a closed
coral wastes food and adds nutrients without benefit. - Deliver food with a pipette or turkey baster.
Squirt a small amount of food directly near (not blasted at)
the extended tentacles. For duncan corals and brains, place food
in the oral groove or near the mouth. For hammers and torches,
bring food close to the sweeper tentacle tips and let the coral’s
natural movement bring it into contact. - Keep the wavemaker in feed mode for 10–15 minutes
after delivering food, then restore normal flow. This gives the
coral time to capture and begin ingesting before flow resumes. - Feed at the same time each day or week. Many LPS
corals learn to associate low-flow periods with feeding and begin
extending tentacles in anticipation. A consistent schedule produces
better coral response than irregular feeding.
Coral Foods Worth Using
| Product | Type | Best For | Notes |
|---|---|---|---|
| Reef Roids (Polyplab) | Fine particle powder | Zoanthids, mushrooms, small-polyp LPS; broadcast feeding | The most widely used coral food, dissolves well, produces strong polyp response in most soft corals and LPS; use sparingly (pinch per 25 gallons) or nutrients spike rapidly |
| Coral Frenzy (Brightwell) | Mixed particle size powder | Mixed reef broadcast feeding | Similar to Reef Roids with slightly different particle size mix; both are effective |
| Frozen mysis shrimp | Meaty, larger particle | Duncan corals, brain corals, large LPS | The best single food for target feeding larger-polyp LPS; strain the liquid before use same as for fish feeding |
| Frozen cyclops | Small crustacean, medium particle | Small LPS, zoanthids, anemones | Smaller than mysis, appropriate for corals that can’t capture a full mysis shrimp |
| Phytoplankton (live or concentrated) | Microscopic algae | Clams, feather dusters, filter-feeding invertebrates | Limited direct benefit for most corals, most zooxanthellate corals can’t capture phytoplankton efficiently; primarily for bivalves and filter feeders |
| Amino acid supplements (Acropower, Coral Amino) | Dissolved amino acids | SPS corals, general coral health supplement | Not a replacement for direct feeding, supplements dissolved organics in the water column that SPS corals absorb through tissue; effective for color enhancement in SPS when used correctly |
Feeding Newly Added Fish, Getting Them to Eat
A newly introduced fish may refuse food for 24–72 hours while it
acclimates to the new environment. This is normal. A fish that
isn’t eating in the first 48 hours is not a fish that needs to be
force-fed, it’s a fish that needs time and a low-stress environment.
If a fish hasn’t eaten by day 3–5, try these approaches in order:
- Offer live brine shrimp, the movement of live
prey triggers a feeding response in almost every marine fish,
including individuals that won’t touch frozen or pellet food.
Once a fish is eating live brine, gradually mix in frozen mysis
over 1–2 weeks to transition to a more nutritious food. - Try a different food form. A fish that refuses
pellets may accept frozen mysis. A fish that ignores mysis
may accept brine. Some wild-caught fish require live food for
the first several feedings before accepting frozen or prepared foods. - Feed at a consistent time each day. Fish
establish feeding associations quickly. A fish that knows food
appears at the same time from the same direction begins anticipating
it and competing for it within a week. - Check for aggression from established fish.
A new fish that’s being chased away from food by an established
tankmate will appear to refuse food when it’s actually being
prevented from eating. Observe feeding dynamics carefully.
See: Why Are My Reef Tank Fish Hiding? - Use garlic extract. Garlic (Seachem Garlic Guard,
or fresh pressed) soaked onto frozen food before adding stimulates
appetite in reluctant feeders. Not a nutritional supplement, a
feeding stimulant. Useful for transitioning wild-caught fish or
recovering fish that have stopped eating.
Feeding Quick Reference
| Topic | Recommendation |
|---|---|
| Fish feeding frequency | 2–3 small feedings per day; 1 fasting day per week |
| Portion size per feeding | Only what fish consume in 2 minutes; no food reaching sandbed uneaten |
| Best primary fish food | Frozen mysis (strained) alternated with quality pellets |
| Frozen food preparation | Thaw in tank water, strain liquid with brine net, rinse with RODI water before adding |
| Tangs and herbivores | Nori clipped daily in addition to regular feedings, non-negotiable |
| Mandarin dragonet | Requires refugium with active copepod culture; not beginner-appropriate without one |
| Soft corals (mushrooms, zoanthids, leathers) | Direct feeding optional; broadcast Reef Roids weekly for growth benefit |
| LPS corals (hammer, torch, duncan, brain) | Target feed weekly with frozen mysis or Reef Roids; use feed mode to reduce flow during feeding |
| SPS corals | No target feeding required; amino acid supplements optional for color |
| NPS corals (sun coral, carnation) | Must be fed every 1–2 days; not beginner-appropriate |
| Nutrient connection | If nitrate or phosphate is rising despite correct maintenance, reduce feeding volume by 30% for 2 weeks and retest |
Feed the Right Amount. Prepare It Correctly. Watch the Water.
Feeding is the most direct lever a reef keeper has over water quality.
Strained frozen food, correct portion sizes, a weekly fast day, and
target feeding for corals that need it produces a tank with stable
nutrients and healthy, actively feeding livestock. The habit of
straining frozen food alone is worth more to long-term water quality
than most equipment upgrades.
Test Your Water After Adjusting Feeding →
See Recommended Fish Foods →
How to Feed Reef Tank Fish and Corals Effectively
Understanding how to feed reef tank fish and corals is crucial for maintaining a vibrant aquarium. Fish and corals in a reef tank need specific types of food to thrive, so learning how to feed reef tank fish and corals effectively will lead to healthier livestock.
