delusion of negation (nihilistic delusion) a depressive delusion that the self, part of the self, part of the body, other persons, or the whole world has ceased to exist. paranoid d's an older term for delusion of grandeur and delusion of persecution; its use is discouraged. delusion of persecution a delusion that one is being attacked, harassed, cheated, persecuted, or conspired against. It is one of the subtypes of delusional disorder.
Oto Catfish. These fish are perhaps the best kind of fish that you can get for the purposes of cleaning away algae from the plant matter in your fish tank. Their favorite type of algae to eat is brown algae, something that most other fish will stay away from.
Perhaps the most popular freshwater algae eater fish are the sucker mouth catfish including Plecostomus (Plecos) and Otocinclus (Otos). While they do a good job on most forms of green and brown algae, especially algae on the tank walls, their mouths are not equipped with rasps that are strong enough to remove stuck on algae from tank walls.