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.
Algae is a major food source for snails. Algae will grow on its own in your tank even without fish present. The more light your tank receives and the warmer the water temperature, the more algae will grow on the tank walls, gravel, decorations and plants. Mystery snails (Pomacea bridgesii) often eat algae off healthy plants but not the plants themselves.