me giving info on fish I have derived from other people even though I haven't kept the fish.
Hello; First thing is that some concepts cover all fish and are not species specific. Overstocking is over stocking regardless of species.
Next thing is that when I comment on a subject with which I do not have personal experience, I try to mention that I do not have hands on experience.
If I am passing thru information I have picked up from others without having my own personal experience with the subject, I try to say "it is reported" to let people know I am passing on. One of the positive outcomes of having language for communication is that we each do not have to do the trial and error and can learn from others with experience.
That said, the craft in language expression can leave a lot to be desired. It can be hard to write about things in a clear and concise manner and then the reader has to be able to read for understanding. I may know what information I intend to convey but fail to express my thoughts well enough for the reader to get a good grasp. Then if the reader tries to pass on what I have said the information may get even more scrambled. This may be the rub in passing on knowledge not gained by personal experience.