This study was planned to investigate parasitic infection of imported ornamental fish, double tail goldfish,
Carassius auratus. A total of 25 experimental fish were examined for parasitic infection. One fish
specimen showed head lesion (1x1cm). Eight different species of parasites were observed on the fish.
The gills showed 100% infection by Dactylogyrus sp. and mean intensity was 35.4. Fins of the fish also
showed high infection (68%) and mean intensity (13.82) by Gyrodactylus sp. Argulus foliaceus infection
on skin and fins was 40% and its mean intensity was found 4.2. Metacercariae of an un-identified
digenean were also found encysted on gill filaments (infection 32%, mean intensity 3.87). Ichthyophthirius
multifiliis infection on fins was found 20% and mean intensity was found 2.4. Trichodina sp. infection on
fins was 12% (with mean intensity 13). Low infection by Piscinoodinium pillulare on fins (8%) and of
Tetrahymena sp. on fins and gills (4%) was also observed. This study has shown that imported double tail
goldfish was not healthy but had parasitic infection. There is an urgent need to have strict check and
control over the import of infected and diseased fishes in Pakistan to protect the local biodiversity of
Pakistan.