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.
Subdued lighting supports the growth of this algae, however as time goes by it usually disappears. Common algae eaters tend to eat it, but old and adult fish will rather wait for pellets or wafers, eventually frozen foods. Bear in mind that 4 or 5 algae eaters will not solve this problem in a week.