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New Zealand Journal of Marine and Freshwater Research abstractsM99065 Received 5 November 1999; accepted 5 April 2000
Chemotherapy of the ciliate Trichodina sp. on juvenile turbot (Colistium nudipinnis) with notes on the susceptibility of fish with abnormal pigmentationB. K. DIGGLES
National Institute of Water & Atmospheric
Abstract Turbot (Colistium nudipinnis (Waite, 1910))
fingerlings reared from a single batch of eggs during the 1998 breeding season
were examined by histopathology during a routine health assessment. Fish
exhibiting pigment abnormalities such as brown coloration, extensive
ambicoloration, or hypomelanisation of the ocular surface were significantly
smaller, and had a significantly higher prevalence of kidney lesions and the
ciliate Trichodina sp. on the gills than did normally pigmented fish.
This suggests that abnormally pigmented fish grew more slowly and were more
susceptible to disease. Additional fish were exposed to 12 different
chemotherapeutic bath treatments to determine the most effective methods of
removing Trichodina sp. Treatments which removed 100% of
Trichodina sp. while providing 100% survival of fish included 200 ppm
formalin for 30 min, 200 ppm formalin for 1 h, fresh water for 30 min, and
25 ppm formalin + 0.08 mg/litre malachite green for 24 h. The recommended
treatment against Trichodina sp. for use in a commercial situation is
200 ppm formalin for 30 min. The significance of these findings to culture of
turbot in New Zealand are discussed. |