Indian nudibranchs from the Predator Tank, Two Oceans Aquarium.
An indian nudibranch "from the wild", showing much brighter colours. Both photos Guido Zsilavecz.
Recently, during a routine cleaning dive in the Predator Tank at the aquarium Guido noticed a small, pale nudibranch. Initially it was thought to be Catriona columbiana, a species found in the harbour, and probably introduced by ships - it normally occurs in the Pacific in North America and Japan. As the water of the aquarium is sourced from the harbour, it would not have been unlikely that somehow it managed to survive the filtration and had taken up residence. On a subsequent dive we searched for it, not expecting to find anything, but instead after turning over a few of the pebbles found it to be quite abundant and, indeed, thriving! From the egg case, and from a few collected specimens, it was however determined that they were not C. columbiana, but Aeolidiella indica instead. The indian nudibranch, as it is commonly called, it not regularly seen on a dive - maybe one must start looking under pebbles as well. Those that I have seen however have been much bolder in colour, as the second image shows. The main characteristics are the same of all animals shown, though, so there is no doubt that the aquarium nudibranch is the indian one.
Nudibranchs of Southern Africa - a guide to the opisthobranch molluscs of southern Africa, T Gosliner, 1987.
Description and revision of some South African Aeolidacean Nudibranchia. TM Gosliner and RJ Griffiths. Annals of the South African Museum, Volume 84, Part 2, July 1981.