Mystery nudibranch

May 14, 2001
From: Melanie

I found about 5 of these critters in my reef tank. They look like they may be babies and
have a light pink body with 10 to 12 iridescent spikes on top. Do you know if they are reef safe?

I have not bought any live rock for several months - but most of my live rock is from Fiji. I have several smaller ones also that dont have any color yet. I think they are breeding in my tank. But I don't know where they are coming from. I don't see any
large ones just tiny ones


Melanie, 2001 (May 14) Mystery nudibranch. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Melanie,
It certainly looks like this animal is breeding in your aquarium. It is an aeolid nudibranch. Aeolids feed on cnidarians (sea anemones, hydroids, corals, soft-corals) but each species feeds on only one or a few species of cnidarian. This animal must have arrived in your aquarium as a very small juvenile, probably on its prey, and been quietly nibbling away at something in your aquarium. If you are now seeing smaller uncoloured specimens I suspect that your aeolid is now into a second generation. The two most likely prey items that they are feeding on would be a soft-coral or a hard coral. If you have either, have a look for egg masses. They will either be a sausage-shaped, jelly-like sac containing lots of small white eggs, or else a spirally coiled ribbon. Have a look at the page on Coral-feeding nudibranchs for an idea of what you are looking for. It is possible that the eggs will be under the colony.

What should you do with them? My biased opinion would be to leave them and see what happens. Alternatively perhaps you can try and find what they are eating by looking for egg ribbons and more animals. Uusually they will be living on their food. If you do find some sign of them, have a look at what damage they are doing, and if it is not enormous perhaps you should just leave them be. The first step though is to see if you can discover what they are doing yourself. I suspect they are a coral feeder but they don't look like any species I am familiar with.
Best wishes,
Bill Rudman.

Rudman, W.B., 2001 (May 14). Comment on Mystery nudibranch by Melanie . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

  1. Elysia sp. from the Seychelles
    From: David K. A. Barnes, August 27, 2007
  2. Glaucid sp. from NE Bali, Indonesia
    From: Lindsay Warren, July 12, 2007
  3. An Aeolid from the Gulf of Oman
    From: Dragan Petkovic, July 5, 2007
  4. Phyllodesmium sp? from Lembeh Strait
    From: Mike Krampf, February 17, 2007
  5. Master of camouflage - unknown aeolid
    From: Erwin Kodiat, January 4, 2007
  6. Chromodorid from Indonesia
    From: Ann Clear, December 21, 2006
  7. Unknown nembrothid from Indonesia
    From: Ann Clear, December 20, 2006
  8. Re: Mystery from the Philippines - final word
    From: Scott Johnson, December 13, 2006
  9. Re: Mystery from the Philippines
    From: Philip Cromwell, December 12, 2006
  10. Mystery from the Philippines
    From: Lara Henry, December 12, 2006
  11. Mystery from the Philippines
    From: Gaetan White, December 8, 2006
  12. Rostanga from Sri Lanka
    From: Marina Poddubetskaia, March 12, 2005
  13. Nembrotha from Malaysia
    From: Isabelle Drouet, February 26, 2004
  14. Favorinus? from sth Queensland
    From: Gary Cobb, February 11, 2004
  15. Unknown Nudi found in the Red Sea
    From: Jason Bell, February 4, 2003
  16. Hoplodoris? from Egyptian Red Sea
    From: Jason Bell, January 31, 2003
  17. Phyllidiella zeylanica? from Indian Ocean
    From: Marina Poddubetskaia , November 16, 2002
  18. Aeolid from Thailand
    From: Erwin Koehler, October 23, 2002
  19. Elysiids from Indonesia
    From: Erwin Koehler, October 21, 2002
  20. Re: Elysiid from the Red Sea
    From: Erwin Koehler, October 3, 2002
  21. An unknown aeolid from Bali
    From: Rika Nozoe, October 3, 2002
  22. Phyllidia melanocera? from Egypt (2)
    From: Michael Mrutzek, September 30, 2002
  23. Phyllidia melanocera? from Red Sea
    From: Michael Mrutzek, September 28, 2002
  24. Need help identifying
    From: Sabine Noack, September 18, 2002
  25. Dermatobranchus from aquarium
    From: Christel Theate, September 18, 2002
  26. Aeolid from the Philippines
    From: Erwin Koehler, July 30, 2002
  27. Eolid from Enewetak, Marshall Islands
    From: Scott Johnson, July 18, 2002
  28. Strange dorid from Hachijo Island, Japan
    From: Shouichi Kato, May 3, 2002
  29. Cephalaspidean from the Philippines
    From: Erwin Koehler, May 3, 2002
  30. Another deepwater slug from Hawaii
    From: Dr. Christopher Kelley, May 2, 2002
  31. Aeolid from the Philippines (2)
    From: Erwin Koehler, April 30, 2002
  32. Elysiid from the Red Sea
    From: Erwin Koehler, March 12, 2002
  33. Elysia from Queensland
    From: Alison Smith, February 24, 2002
  34. Chromodorid 'conference' in Indonesia
    From: Stuart Hutchison, December 22, 2001
  35. Unknown sponge feeder
    From: Jim Cruise, October 2, 2001
  36. Flabellina from the Philippines
    From: Erwin Koehler, August 10, 2001
  37. Yellow aeolid on hydroid
    From: Tony Wu, April 12, 2001
  38. Need help ID this nudibranch/slug
    From: Planoi, January 1, 2001
  39. Need help ID an sea slug/nudibranch?
    From: Win, December 30, 2000
  40. Elysia or Thuridilla from Coral Sea
    From: Des Paroz, October 22, 2000
  41. What is this?
    From: Mary Jane Adams, June 17, 2000
  42. Aeolid from Papua New Guinea
    From: Ray Izumi, May 12, 2000

Show factsheet and all related messages