By looking at a blood smear under a microscope, parasitic diseases such as filariasis, malaria, or babesiosis, can be diagnosed. This test is done by placing a drop of blood on a microscope slide. The slide is then stained and examined under a microscope.

see the links below...

Article Guide to the identification of fish protozoan and metazoan p...

Article The identification of parasites in fish tissue sections

http://fisheries.tamu.edu/files/2013/09/Introduction-to-Freshwater-Fish-Parasites.pdf

https://krishi.icar.gov.in/jspui/bitstream/123456789/3878/1/120-Book%20chapter%20Rajesh%20Katoch%20%281%29.pdf

https://edis.ifas.ufl.edu/publication/FA113?downloadOpen=true

Without more information or a clearer image, it is difficult to accurately identify the parasites in the photo you provided. In order to accurately identify the parasites, it would be helpful to have more information such as the location where the Tilapia were collected, the size and shape of the parasites, and any distinctive features or characteristics.

There are many different types of parasites that can infect fish, including protozoa, worms, and crustaceans. Some common fish parasites include flukes, tapeworms, lice, and copepods. It is important to accurately identify the parasites in order to determine the appropriate treatment and prevent the spread of these parasites to other fish.

If you are unable to identify the parasites on your own, you may want to consider seeking the help of a veterinarian or a fish health specialist. They will have the necessary training and expertise to identify the parasites and recommend appropriate treatment.

Without any information related to fish (fish age), culture( type and location), parasite and season the figures of parasite are unknown

How can you define them as parasites?

Coming from the intestines, they can have origin on the prey/food ingestion and not have a parasitic relationship with these fish...