Pest Control Checklist for Reef Keeping

A dedicated coral quarantine tank gives you time to spot eggs, bite marks, tissue irritation, or hidden hitchhikers before they reach the display. Use stable salinity around 1.025 to 1.026 SG, temperature 77 to 79 F, and moderate flow so stressed frags still extend enough for inspection.

Coral dips can knock off flatworms, nudibranchs, red bugs, and other mobile pests that are easy to miss on first inspection. Follow the dip manufacturer's contact time closely, rinse in clean saltwater after treatment, and remember that most dips do not kill eggs.

Aiptasia, vermetid snails, bryopsis, bubble algae, and pest eggs often hide in crevices on plugs and encrusted bases rather than on coral tissue itself. Re-mounting healthy tissue to a clean plug reduces the chance of transferring persistent pests into the display tank.

Many pests are easiest to see with a flashlight, jeweler's loupe, or macro lens rather than under heavy blue spectrum. Focus on shaded areas, fold lines in tissue, and the underside of plates where montipora-eating nudibranch eggs and flatworms are commonly found.

Aiptasia, majano anemones, predatory crabs, parasitic snails, and nuisance algae frequently arrive on non-coral additions. Isolating these items helps prevent introducing pests that coral dips will not address.

Tweezers, cutters, turkey basters, specimen cups, and even towels can move pests or eggs between systems. Color-code or label quarantine tools so accidental cross-contamination does not undo weeks of careful observation.

Still water makes it much easier to see flatworms on glass, nudibranchs on montipora edges, and Aiptasia tucked between polyps or rock crevices. Spend 5 to 10 minutes checking the same colonies each week so changes are obvious.

Red bugs often cause dull coloration, poor daytime extension, and a generally irritated look, especially on smooth-skinned Acropora. Use a magnifying lens to inspect branch tips and axial areas where tiny yellow-orange specks may be visible.

Montipora-eating nudibranchs often leave clean white feeding scars on plating and encrusting montis, especially on shaded edges. Their egg spirals are commonly found on the underside or in folds, so checking only the top surface often misses the real problem.

Convolutriloba and Acropora-eating flatworms can multiply before obvious coral damage is noticed. A flashlight inspection at an angle helps reveal their outline on smooth surfaces and coral flesh, especially during lower flow periods.

These pest anemones often establish in low-visibility zones first and then spread by budding or fragmentation. Catching one or two early is far easier than dealing with dozens embedded throughout the aquascape.

Not all RTN, STN, or fading is caused by alkalinity swings, low nutrients, or lighting changes. When a single colony declines while neighbors remain healthy, inspect for pests before making major system-wide adjustments.

Use an Aiptasia-specific paste or kalkwasser slurry with pumps off so the product stays on the oral disc and column. Avoid scraping or blasting the anemone, because damaged tissue can lead to additional spread across nearby rockwork.

Large flatworm die-offs can release toxins that stress or kill fish and corals, especially in smaller systems. Use airline tubing into a filter sock or waste bucket to reduce biomass first, then prepare fresh carbon and a water change.

Because eggs survive most dips, one treatment is rarely enough to break the life cycle. Remove egg masses manually with a blade, toothbrush, or pick, then continue a scheduled series of inspections and dips for several weeks.

Milbemycin-based treatment can be highly effective, but it can also affect crustaceans such as copepods, ornamental shrimp, and some crabs. Verify the pest first and plan temporary relocation or expected losses before treatment begins.

Vermetid mucus nets can irritate nearby coral tissue and trap detritus around frags. Snap the tube near the base and seal the opening with reef-safe glue or epoxy to prevent regrowth from the remaining structure.

Use forceps or twist gently at the holdfast during a water change so escaped cells are easier to export. If the patch is dense and close to coral bases, removing the rock for controlled cleaning is often the safer option.

Corals already stressed by pests are less tolerant of parameter swings, especially rapid alk changes. Stability matters more than chasing an exact number, so avoid big dosing corrections while colonies are recovering.

Ultra-low nutrients can slow recovery and reduce tissue resilience after bites, dips, or repeated handling. A practical range for many mixed reefs is nitrate 2 to 15 ppm and phosphate 0.03 to 0.10 ppm, adjusted for system goals and coral response.

Carbon helps remove organics, toxins, and residual treatment compounds that can irritate fish and corals. Replace or refresh it promptly after major treatment events, especially if you notice unusual coral retraction or fish distress.

Having mixed saltwater ready is one of the best safeguards when treating toxins, unexpected coral slime, or oxygen stress. Match temperature, salinity, and alkalinity closely so the water change solves the problem without creating another one.

Some pest treatments and heavy coral stress events can reduce oxygen or increase bacterial activity. Point a powerhead toward the surface, open skimmer air intake, and watch fish breathing rate closely for the next several hours.

Combining dips, in-tank chemicals, aggressive manual cleaning, and large parameter adjustments can overwhelm sensitive corals. Space interventions out so you can judge what worked and minimize compounding stress.

Many pests hide well during the first pass, and new damage often becomes visible after the coral reopens. Compare the same areas of the colony, especially margins, undersides, and previously affected tissue.

Peppermint shrimp may help with small Aiptasia populations, and some wrasses may reduce flatworms or nudibranchs, but results vary widely. Biological control should support, not replace, quarantine, manual removal, and direct treatment.

Coral pests often cause subtle changes that are easy to miss day to day under shifting blue-light viewing. Consistent photos under white light help confirm whether tissue loss is still active or the colony is finally stabilizing.

Notes on eggs, juveniles, bite marks, and coral response make it easier to time repeat treatments accurately. Detailed records are especially helpful for pests with multi-week cycles such as montipora-eating nudibranchs or persistent Aiptasia outbreaks.

Pests rarely stay confined to one frag for long, especially in SPS-dense systems where colonies touch or share flow paths. Expanding the search early can prevent a localized issue from becoming a full-tank infestation.

A recovering coral may need slightly lower PAR, gentler flow on damaged tissue, or more consistent feeding support depending on species. Fine-tuning husbandry after pest removal often determines whether a colony regains color and growth or continues to decline.