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.
Soft Green Algae. The main food of Otocinclus is algae. They will eat the soft green algae that grows on the surfaces of the tank and its contents. This surfaces include the inside of the tank walls, gravel, decorations, and plants. This soft algae isn't to be confused with green spot algae that you can barely get off with a razor blade.
They survive for a time in freshwater and eat algae, but they require saltwater to breed. So nerites are not the best choice for a freshwater aquarium. Fish are only one type of animal that eats algae. There are many algae-eating snails, shrimp and clams that can be interesting additions to your tank.