Deadly Plants to Koi & Goldfish

The following list of harmful plants comes from an article published in KOI USA several years ago.
Plant	Poisonous Part
Amaryllis	Bulbs
Azalea	Leaves
Balsam Pear	Seeds, outer rind of fruit
Baneberry	Berries, roots
Bird of Paradise	Seeds
Black Locust	Bark, sprouts, foliage
Blue-Green Algae	Some forms toxic
Boxwood	Leaves, stems
Buckthorn	Fruit, bark
Buttercup	Sap, bulbs
Caladium	Leaves
Calla Lily	Leaves
Castor Bean (Castor Oil)	Beans, Leaves
Challice Vine	All parts
Cherry Tree	Bark, twigs, leaves, pits
Christmas Candle	Sap
Coral Plant	Seeds
Daffodil	Bulbs
Daphne	Berries
Datura	Berries
Deadly Amanita	All parts
Death Camas	All parts
Deiffenbachia	Leaves
Delphinium	All parts
Eggplant	All parts but fruit
Elephant's Ear (Taro)	Leaves, stem
English Ivy	Berries, leaves
False Henbane	All parts
Foxglove	Leaves, seeds
Golden Chain	All parts, especially seeds
Hemlock, Poison	All parts, especially roots and seeds
Hemlock, Water	All parts, especially roots and seeds
Henbane	Seeds
Holly	Berries
Horse Chestnut	Nuts, twigs
Hyacinth	Bulbs
Hydrangea	Flower bud
Indian Turnip (jack-in-the-pulpit)	All parts
Iris (Blue Flag)	Bulbs
Java Bean (Lima)	Uncooked bean
Jerusalem Cherry	Berries
Jimsonweed	Leaves, seeds
Juniper ( J. virginiana)	Needles, stems, berries
Lantana	Immature berries
Larkspur	All parts
Laurel	All parts
Lily of the Valley	All parts, including water
Lobelia	All parts
Locoweed	All parts
Lords and Ladies	All parts
Marijuana	Leaves
Mayapple	All parts, except fruit
Mescal Bean	Seeds
Mistletoe	Berries
Mock Orange	Fruit
Monkshood	Leaves, roots
Morning Glory	All parts
Narcissus	Bulbs
Nightshades (All)	Berries, leaves
Oak	Acorns, foliage
Oleander	Leaves, branches, nectar of blossoms
Philodendron	Leaves, stem
Pikeweed	Leaves, roots, immature berries
Poinsettia	Leaves, flowers
Poison Ivy	Sap
Poison Oak	Sap
Potato	Eyes and new shoots
Privet	All parts, including berries
Rhododendron	All parts
Rhubarb	Leaves
Rosary Peas	Seeds
Skunk Cabbage	All parts
Snow on Mountain	All parts
Snowdrop	All parts, especially buds
Sweet Pea	Seeds and fruit
Tobacco	Leaves
Virginia Creeper	Sap
Wisteria	All parts
Yam Bean	Roots, immature pods
Yew (American, English, Japanese)	Needles, seeds