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Acro Eating Flatworms - AEFW

Acro Eating Flatworms (AEFW) are a type of flatworm that can be a significant concern in the marine aquarium hobby, particularly among acro collectors. These flatworms are particularly found on wild-caught and maricultued acro colonies especially from the Indo-Pacific region, which are prized by many reef hobbyists for their intricate growth patterns and vibrant colors. These flatworms can be introduced to aquariums when Acropora corals are added to the tank.

Pic Source - Reefbum (

Hobbyist who've dealt with AEFW know the havoc they can cause in an acro heavy reef tank. Acro Eating Flatworms feed on the tissue of Acropora corals. They can quickly multiply in numbers and cause damage to the coral by consuming its flesh. This can lead to tissue recession, color loss, and even the death of the coral if not addressed promptly.

AEFW are particularly had to spot/identify. Almost translucent under blue aquarium lighting, they are often more visible under white lighting. If healthy acro colonies have lost color, and polyp extension, one should use a turkey baster to blow on the coral. More often or not, one may see flatworms blown off the coral. Unfortunately, unlike their cousins the Red planaria flatrowms, wrasses dont spot/eat AEFWs.

Bite Marks on the under side of the acro are another way of an identifying AEFW infestation. These are more visible under white light, or if the coral is outside of water

There are multiple ways to tackle this problem, and they can be looked up online on portals such as Reef 2 Reef ( or Bulk Reef Supply videos on Youtube ( . But the best one is - prevention. Always QT wild-caught and maricultured acros in a separate tank. Or buy only aquacultured frags from vendors and hobbyists.

If it helps, here's some of the items others in my network have noticed while fighting AEFW

  • Warmer water temp quickens egg hatching. E.g. water thats 77-80 deg F, takes around 11 days for eggs to hatch, and 35 days for flatworms to reach sexual maturity

  • Hatchlings which can swim as well as crawl. So putting an infected colony away from healthy acro's doesn't help. Healthy ones, will get affected!.

  • Hatchlings can survive between 1 and 12 days in the absence of Acropora. So going fallow of all acros, for minimum of 2 weeks is the only real way of tackling AEFW and breaking the cycle.

  • Luckily levamisole e.g. common Coral dips, does work pretty well against AEFW. I suggest, removing ALL acros and doing large scale dips. Every OTHER week. For 3 rounds, i.e. 6 weeks total. This will kills adults, and weekly dips will to target new hatchlings after they emerge from their protective egg capsules.

I am also available for hourly consultation to navigate hobbyists thru the menace of AEFW. PM me.

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