Protein poisoning in fish

Hey all, I'm new to the forum and still working on my intro! In the meantime, I have a question. At the last GSAS meeting, the speaker gave us a nugget about fish eating too much protein, leading to some jelly like growth on their fins. He mentioned that you could get the fish on a daphnia diet for a month to help resolve this. Is this a problem folks have had and do you have more info on it?

Rarely seen in the hobby as most people don't feed enough high protein foods to their fish. It's usually only in the case of tons of high fat protein foods that a live. Like baby brine shrimp and black/tubifex worms.

Ive never heard of this... tried to google info on it and did not find anything to satisfy my curiosity.

I use pellets as a main food with an occasional treat of frozen food so overall very balanced diet. I guess I would not see this type of issue. If anyone has any more info on this would like to hear about it.