I recently read a very in depth article about parasites that afflict aquarium fish. Parasites reproduce and infect fish in at least three different ways using various hosts. The article was a bit over my head but impressed upon me the need for quarantining new plants and new fish. New plants can have snails on them that are hosting parasites and I did not know that. Since many fish and plants are raised in large outdoor ponds the likelihood of parasites is very real. Feeder fish found in pet shops are another source of parasites. If you need them raise your own. I kind of think that most of the maladies found in the fish being discussed could be related to internal parasites.
