STUDIES ON THE OCCURRENCE OF ACTINOSPOREAN STAGES OF FISH MYXOSPOREANS IN A FISH FARM OF HUNGARY, WITH THE DESCRIPTION OF TRIACTINOMYXON, RAABEIA, AURANTIACTINOMYXON AND NEOACTINOMYXON TYPES

Actinosporean infection of the oligochaete fauna living in the mud and on the vegetation of fish ponds used for rearing common carp in polyc ulture was studied during a one-year survey at a fish farm in Hungary, located south of Budapest. Twenty-eight actinospore types were isolat ed from the oligochaetes Tubifex tubifex, Branchiura sowerbyi, Limnodr ilus hoffmeisteri, Nais elinguis, and Stylaria lacustris collected dur ing the survey, which could be classified into the triactinomyxon, raa beia, aurantiactinomyxon and neoactinomyxon groups. Drawings depicting individual actinospore types are presented on plates and their charac teristic dimensions have been summarised in tables. The prevalence and seasonality of actinosporean infections observed in the various oligo chaete species have been illustrated graphically. Infection by actinos pores showed a pronounced seasonality. In the spring, summer and autum n the prevalence of raabeia infection in Branchiura exceeded 90%, whil e in the winter it dropped to 42%. A similar phenomenon could be obser ved for aurantiactinomyxon infection, while neoactinomyxon infection r eached its peak in the autumn. In Tubifex, Limnodrilus, Nais and Styla ria species the peak of actinosporean infection occurred, with minor d ifferences, in the spring and summer. Actinosporean infection in the i ndividual Oligochaeta species showed much higher prevalence values tha n had been reported in the literature, which can be explained by the n ovelty of the examination technique used. It cannot be decided with ab solute certainty which myxosporean developmental stage the different a ctinospore types described during this survey represent of the species of Myxosporea parasitic in the given ponds. This would require an exp erimental study for which the data presented here may serve as a basis .