The black oval/round looking critters are flukes. These are harmless to humans if cooked. These are present in waterfowls intestine and when they pay a visit to your pond they leave some these guys behind. The the crustaceans snails etc.. pick them up then in turn get eaten buy the gills and they work there way into the meat. Now after that I dont know what happens to them. Sorry i know the story was gettin good.

The yellow critters i have seen in my crappie and I am pretty sure you can consume those too if cooked. Basically most parasites found on or in fish can be cooked to safe eating. it is just a matter of what you like looking at while eating

I just told my wife the fillets came PRE-seasoned:)