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.
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.