Red Bugs on Acropora: Identification, Treatment and Prevention
Your Acropora colony looks healthy by every metric — parameters are stable, growth tips are extending, yet the polyps never fully open, and the colour seems perpetually washed out. The culprit may be too small to see without magnification. Red bugs acropora treatment is a topic every SPS keeper eventually confronts, because Tegastes acroporanus is one of the most insidious pests in the reef hobby. This guide from Gensou Aquascaping at 5 Everton Park, Singapore covers identification, the proven treatment protocol, and how to prevent reinfestation.
What Are Acropora Red Bugs?
Tegastes acroporanus is a tiny parasitic copepod — not an insect, despite the common name — that lives exclusively on Acropora coral tissue. Adults measure just 0.5-1.0 mm, appearing as tiny yellow-red or orange specks that scuttle across the coral’s surface. They feed on coral mucus and tissue, causing chronic irritation that suppresses polyp extension and dulls colouration. A heavily infested colony may have hundreds of red bugs, though individual worms are barely visible without a magnifying glass or macro photograph.
How to Confirm an Infestation
Red bugs are host-specific to Acropora and will not be found on Montipora, Stylophora or other SPS genera. Examine your Acropora colonies closely using a magnifying glass or take a macro photo with your phone and zoom in on the coral’s surface. The bugs appear as tiny moving dots, typically concentrated around branch tips and between polyps. Another diagnostic clue: if your Acropora corals have poor polyp extension while all water parameters test correctly and other SPS species in the same tank look fine, red bugs should be your primary suspect.
The Interceptor Treatment Protocol
The standard treatment uses Interceptor (milbemycin oxime), a veterinary heartworm medication for dogs. One tablet of Interceptor for dogs weighing 11-25 kg (containing 11.5 mg milbemycin oxime) treats approximately 380 litres of tank water. Crush the tablet into fine powder, dissolve in a small amount of tank water and distribute evenly into the system. A single dose kills all adult red bugs within hours.
However, Interceptor does not kill eggs. Repeat the treatment three times at intervals of 5-7 days to catch newly hatched bugs before they reach reproductive maturity. Three doses over approximately 14-21 days is the minimum protocol. Some hobbyists opt for four treatments for extra assurance.
Important Precautions
Interceptor is lethal to crustaceans. All shrimp (cleaner shrimp, peppermint shrimp, fire shrimp), crabs (hermit crabs, emerald crabs, decorator crabs), pods and other crustacean invertebrates must be removed from the tank before treatment. Transfer them to a separate holding container with aeration and return them 24 hours after each treatment, following a full water change of 25-30 percent with activated carbon running to remove residual medication.
Snails, corals and fish are unaffected by Interceptor at therapeutic doses. Monitor your tank carefully during treatment nonetheless — any unusual behaviour warrants immediate water change and carbon filtration.
Alternative: Coral Dipping
For hobbyists who prefer not to treat the entire system, individual coral dipping offers a targeted approach. Remove each Acropora colony and dip in Bayer Advanced insecticide (10 ml per litre of tank water) or CoralRx for 10-15 minutes with gentle agitation. Red bugs will release from the coral into the dip solution. Rinse the coral in clean saltwater before returning it to the tank. This method requires removing and dipping every Acropora in the system — missing even one colony allows bugs to reinfest treated corals.
Dipping must also be repeated every 5-7 days for three cycles to break the reproductive cycle and catch hatching generations.
Sourcing Interceptor in Singapore
Interceptor requires a veterinary prescription in most jurisdictions, including Singapore. Consult a veterinary clinic — explain the aquarium use and most vets will write a prescription without difficulty. Some reef hobbyists source it through online veterinary pharmacies or arrange group purchases within local reefing communities on forums and chat groups. A single box containing six tablets treats a large system multiple times, making it cost-effective when shared among several hobbyists. Expect to pay $60-$100 SGD per box.
Prevention
Dip every new Acropora frag in a coral dip solution for 10-15 minutes before adding it to your display. Inspect frags closely under magnification — both the coral surface and the frag plug — before purchase. Quarantining new SPS frags in a separate system for two to three weeks with repeated dipping provides the most reliable prevention. Given how commonly red bugs circulate through the Singapore reef-trading community, a strict dip-and-quarantine protocol is not optional for serious SPS keepers — it is essential.
After Treatment: What to Expect
Within days of completing the Interceptor protocol, treated Acropora colonies typically show noticeably improved polyp extension. Colour begins to deepen over the following weeks as the corals recover from chronic irritation. The transformation can be dramatic — colonies that appeared mediocre for months suddenly reveal their true colour potential once the parasitic burden is lifted. It is one of the most satisfying fixes in the hobby, turning underperforming SPS corals into the vibrant centrepieces they were always meant to be.
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emilynakatani
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