Spironucleus vortens, a possible cause of hole-in-the-head disease in cichlids

Hole-in-the-head disease is recorded in 11 discus Symphysodon discus Heckel , 1840 and 1 angelfish Pterophyllum scalare Lichtenstein, 1823 obtained fro m local aquarists within the Southwest of the UK. Spironucleus vortens Poyn ton et al. 1995, was isolated from the kidney, liver, spleen and head lesio ns of discus showing severe signs of the disease and from the intestines of all fish. The hexamitid was also recorded from the head lesions of the ang elfish. The identity of these flagellates was confirmed as S. vortens on th e basis of topographical features seen with the aid of SEM. A modified in v itro culture method was successfully developed for the detection, isolation and long-term maintenance of S. vortens. The flagellate was sub-cultured a t 3 to 5 d intervals, new media being supplemented with fresh liver from Or eochromis niloticus (Linnaeus, 1757) free from infection, The results are d iscussed in relation to S. vortens as the causative agent for hole-in-the-h ead disease following systemic infection via the digestive tract.