Abstract:
The parasite fauna of the two cat fishes, Pseudarius jella and Mystus gulio,
frequently found in brackish water of the Southern coast of Sri Lanka and their
population levels were investigated in an attempt to estimate their relative
importance. The factors which may be responsible for the difference of fauna and
changes of population levels in the two host species were taken into consideration.
One hundred and fifty three Pseudarius jella specimens and 50 Mystus gulio
specimens were surveyed within a period of one year. The proportion of P. jella
and M. gulio was not equal in samples.
Six parasite species, 2 monogeneans, 1 melaccrcaria, 1 nematode, I acanthocephala
and I copepode were found on P. jella, while 10 parasite species, I tricodinid. I
monogenean, 3 metacercariae, I adult trematode, 1 cestode and 1 nematode larva,
and 2 acanthocephalans were found on M. gulio. Only cyathocotylid melaccrcaria
and 1 acanthocephalan species were common to both hosts. All the parasites found
and even some genera, were not previously recorded in Sri Lanka. Trichodina sp.,
gill filament monogeneans, Cyathocotylid metacercaria and acanthocephalans were
the most important parasites. The considerable difference of the parasite fauna was
not due to the host specificity only, as some parasites belonging to less specific
parasite groups were restricted to one host. Presence of stages entering with
plankton only in M. gulio, revealed that the fish is planktivorous, in addition to
being carnivorous. Restriction of 2 metacercariae to M. gulio suggested a
behavioural difference of ccrcariae and/or host which favours its entering.
