Chilodonella spp. at Four Fish Farms in Northern Finland

Abstract

A total of 4.1% infestation with Chilodonella spp. was found among fish studied in 144 tanks in 1987-1989, representing 14.0% of the tanks in which fish are reared at four salmonid farms in northern Finland. Two species were found, C. hexasticha and C. piscicola, and both occurred on salmon (Salmo salar L.), sea trout [S. trutta m. trutta (L.)] and brown trout [S. t. m. lacustris (L.)]. Variability was observed in the length and width of the C. piscicola specimens and the number of ciliary rows or kineties. Large specimens which had more kineties than average for C. piscicola were found mainly on the skin of salmon aged 1-2 years. The number of kineties in the right ciliary band was found in stepwise logistic regression analysis to be of importance when typing C. piscicola specimens. Fingerlings were found to be more susceptible to Chilodonella infestation than older fish, and mortality varied in the range 2-10% in the course of the epizootics in the three fish species. Most mortality cases were caused by C. hexasticha, occurring mainly on the gills of the fish. Chilodonella piscicola was most often found in salmon and occurred at lower water temperatures than C. hexasticha (mean water temperature when found for the first time being 13 degrees C and 16 degrees C, respectively).

Control of freshwater fish louse Argulus coregoni: a step towards an integrated management strategy

“…Other chemicals previously used as bath treatments against argulids include salt (NaCl) and formalin (Kabata 1985). Fish farmers in Finland generally use 10 to 20 g l -1 sodium chloride solution over a period of 20 to 60 min against Chilodonella ciliates on fish (Rintamäki et al 1994). According to Singhal et al (1986), dipping of infested fish in 30 mg l -1 sodium chloride for 2 to 5 min is very effective treatment against A. indicus.…”

“…Two concentrations of each chemical were tested; dosing choices were based on the treatment ranges used in Finnish fish farming (e.g. Rintamäki et al 1994, Rintamäki-Kinnunen & Valtonen 1997, Rintamäki-Kinnunen et al 2005a. The chemicals and their concentrations were: (1) formalin 0.6 and 0.4 ml l , and (4) malachite green/formalin (3.7 g of malachite green mixed in 1 l formalin) 0.025 and 0.0125 ml l -1 .…”

“…Intensification of aquaculture has lead to the development of favourable conditions for a variety of fish disease-causing agents (Rintamäki et al 1994, Rintamäki-Kinnunen & Valtonen 1997, Suomalainen et al 2005, crustacean ectoparasites among others (Menezes et al 1990, Hakalahti & Valtonen 2003, Costello 2006. Parasitic crustaceans are epithelial browsers that harm the protective epithelium of the fish and evoke stress responses by attaching and feeding on fish skin or gills.…”

“…Thus, there is an urgent need to further develop management of Argulus populations (see also Taylor et al 2006). The specific aims of the present study were to: (1) test several types of methods (chemical, biological and mechanical) to prevent and control A. coregoni infestations, (2) pinpoint the most vulnerable stages in the parasite life cycle against which the specific control attempts could be targeted, and (3) based on the present results and previously published work, create a framework for sustainable management of A. coregoni populations.The chemicals used were sodium chloride, formalin, potassium permanganate and a malachite-green/formalin mixture, all of which are or have been common treatments against ectoparasites in Finnish fish farming (Rintamäki et al 1994, Rintamäki-Kinnunen & Valtonen 1997. Although the use of malachite-green is banned in most European countries (from 1 October 2001 onwards in Finland), it was included owing to its traditional and most effective use as a bath treatment against ectoparasitic ciliate and fungal infections such by Ichthyophthirius multifiliis and Saprolegnia spp., respectively (Willoughby & Roberts 1992, Rintamäki-Kinnunen et al 2005a.…”

“…The effects of 4 different chemical treatments were tested on survival of Argulus coregoni under laboratory conditions. These chemicals have traditionally been employed at Finnish fish farms for managing various ectoparasites (Rintamäki et al 1994, Rintamäki-Kinnunen & Valtonen 1997. Two concentrations of each chemical were tested; dosing choices were based on the treatment ranges used in Finnish fish farming (e.g.…”