As ectoparsites are on the surface, you can get them on the skin, gills, fins, head, such as Lernaea, Argulus, Dactylogyrus, Ichthyophthirius multifilis etc. looking for endoparasites, do the autopsy look for parasites in the liver (Euclinistomum), stomach, and intestine (Pallisentis) . You will get enormous parasites from catfishes, Murals etc.

You need a good hand lens to really see ectoparasites. For endoparasites you need to work on the different organs.kindly read articles to understand the step by step process

Dear Fellow

Inoculation is usually used for bacterial infections while for ectoparasitic introduction in fish is carried through challenge infections. In this context, gill parasites are quite prevalent in diverse fish species, which can be used easily for such kind of research studies.

Regards

you can study the effect of parasites on blood indices that is good indicator.

you can related the being of parasites especially the internal parasites to their food item,

so you must study their food items.

Regards