The rules vary from person to person depending on who you talk to...
Some say 'Scales Only' and then 'Flesh Only'.
Scales mean they don't have skin parasites like cat fish do,
And flesh only means you aren't eating the organs where you can contract things like Liver Fluke and Lung Fluke...
Some people say not to eat the flesh of scavenger fish, even if the have scales, (like different carp species),
But the flesh of freshwater predator hunting fish, like bass or blue gill would be safe to consume.
I can't vouch for this, but I've heard it all at one time or another.
Again, It's definite you can't eat fresh water fish organs, Heart Fluke, Lung Fluke, Liver Fluke, a dozen different kinds of worms and parasites, ect.
Others say you can eat the flesh from any fresh water fish, but not the organs.
I don't subscribe to that simply because I've seen colonies of parasites on catfish that have eaten through the skin, so they MUST be in the meat.
NEVER EAT THE ORGANS OF FRESH WATER FISH!
Survival School in the military 30 odd years ago said you could eat the flesh from scaled fresh water fish, but not organs, skin, scales or anything from fish that had skin.
Again, I don't eat raw fish, I don't know about the validity of the military training information from 30+ years ago,
And I can't tell you if it's been updated in the last 30 years...
I know people do eat trout raw, and I know the Asians, particularly the Chinese immigrants, go nuts for carp around here and they sometimes eat it raw...
And that would appear to go against the teaching of the military instructors I had, so some species are evidentially safe, I just can't tell you which ones!
when i prepare fresh water fish of any kind, to be eaten raw/cold cured.
remove fillets, remove skin from flesh, debone completly, wash thoroughly in clean water, inspect for parasites and remove if visible, dice meat into 1" cubes, for 2.5lb of meat- juice from 3 lemons and 1/3 cup sugar, mix thoroughly by hand in bowl cover with lid and leave for 3-4 hours, add salad and serve cold.
this will feed 5 adults.
When I took my sea survival training in the early 1970s we were taught that fresh water fish and eels must be cooked to kill harmful micro-organisms, but that saltwater fish with scales, rather than smooth skin could be eaten raw. Avoid blowfish, and any salt water varieties not caught in open ocean, during migrations, due to pollution, micotoxins in algae, etc. See: