How harmful is oleander to goldfish?

Oleander, also known as willow-leaf peach, belongs to the genus Nerium in the family Apocynaceae. It has been introduced into China for a long time and is cultivated in various places; it is a common ornamental flower in gardens. The entire oleander plant is highly toxic, and accidental ingestion by humans or livestock is dangerous. There are numerous instances in which oleander leaves, petals, fruits and small branches falling into goldfish tanks have caused the death of all the young and adult goldfish. The reason is that oleander mainly contains cardiac glycosides such as yellow oleandrin A, yellow oleandrin B, oleandrin A, yellow oleandrin A monoside methyl, yellow oleandrin A monoside ethyl and yellow oleandrin C, which have highly toxic effects on fish and can cause acute poisoning and death in goldfish.

The methods of prevention and treatment are: 1) avoid planting oleander beside goldfish tanks; 2) if oleander is found to have been brought in by wind or other means, immediately remove the fish, change the water, and disinfect and sterilize the fish tank with potassium permanganate to ensure the safety of the goldfish.