For fish that produce venom harmful to humans, see
Venomous fish.
Fish toxins or fish stupefying plants have historically been used by many
hunter gatherer cultures to stun fish, so they become easy to collect by hand. Some of these
toxins paralyse fish, which can then be easily collected.[1] The process of documenting many fish toxins and their use is ongoing, with interest in potential uses from medicine, agriculture, and industry.[2]
Theory
Use of the herbal fish poisons has been documented in a number of sources involving catching fish from fresh and sea water.[3]
Tribal people historically used various plants for medicinal and food exploitation purposes.[4] Use of fish poisons is a very old practice in the history of humankind. In 1212 AD, King
Frederick II prohibited the use of certain plant
piscicides, and by the 15th century, similar laws had been decreed in other European countries, as well.[5] All over the globe, indigenous people use various fish poisons to kill fish, including America[6] and among
Tarahumara Indians.[7][full citation needed]
Herbal fish-stupefying agents are proven means of fishing. Many of these plants have been used for a long time by local people, and have been tested and found to have medicinal properties, such as Careya arborea, which is used as analgesic[8] and antidiarrheal.[9] Some of the plants, such as C. collinus, are traditional poisons used in the different part of the country.[10][11] Bark extracts of Lannea coromandelica caused lysis of cell membranes followed by fragmentation of cellular materials.
California buckeye (Aesculus californica) is a widespread tree in the
California oak woodlands and
chaparral. The large orange-colored fruit is leached in warm water, with the resultant
aesculin mixture then applied to pools in slow-moving streams to stun fish.[13]
California Natives also used crushed leaves of Croton setiger as a fish toxin much like soaproot and passed this technique on to later immigrants.[15]
The extremely toxic (to humans),
tropane alkaloid-containing shrub Latua pubiflora (family
Solanaceae) was used formerly by the
Huilliche people of the
Los Lagos Region of southern
Chile to catch fish in slow-flowing rivers - either alone or in combination with the juice of Drimys winteri (
Winteraceae) - the latter being a fish poison in its own right. The poison did not kill the fish outright, but merely made them torpid enough to be caught easily.[16][17]
Olax in the family
Olacaceae is a climber with compound, dark-green leaves and white bark. This is the most extensively used fish poison among the
Gondi of India. Typically in summer, the leaves of this plant are dried and powdered. About 1 kg of powder is mixed into water about 5 ft (1.5 m) deep in ponds, usually in the summer. Fish are stunned by the poison and rise to the surface, where they are easily collected by hand. If stunned fish are immediately reintroduced into clean water, they become active. To get good results from the Olax (or korkat), the temperature needs to be high.
Careya arborea in the family
Lecythidaceae is a large deciduous tree with simple large
obovate leaves, large fruit and dark gray bark found in parts of Asia. The root bark is crushed and mixed in water. Upon its admixture, water blackens.
Cleistanthus collinus in the family
Euphorbiaceae (odcha in Gondi) is a medium-sized tree mainly found around villages in Sri Lanka. Young tender shoots of this species are used for fish stunning. The shoots are crushed with water on a stone, and a paste is mixed into the water.
Lannea coromandelica in the family
Anacardiaceae is a medium-sized to large deciduous tree with a spreading crown and stout branches. The leaves are compound, the bark is whitish or gray, and it has small, yellowish or purplish flowers. Flowers and fruits appear between February and June. Fruits (red, compressed, reniform, and single-seeded) of this plant are crushed and mixed in water. It is abundant in the
Mendha-Lekha forest of
Maharashtra.
Costus speciosus in the family
Costaceae is an erect, succulent herb, up to 2.7 m tall and with a tuberous rootstock, which is crushed and mixed in water for fish stunning in India. Apart from its use as a fish stunning agent in Mendha,
tubers of bese mati are consumed after boiling.
Madhuca indica in the family
Sapotaceae is a large tree, with seeds yielding edible oil. After the removal of the oil from seeds, the remaining cake is used for fish stunning in India. This cake is locally known as gara-dhep. The cake is boiled in water and mixed into water. A 0.5-kg cake is sufficient for a 100 ft2 pond. It is an effective agent, but fish usually die from its application.
Pterocarpus marsupium in the family
Fabaceae is a large tree with simple leaves found in South Asia and Nepal. Its gray bark is used for fish poisoning, crushed and mixed in water.
Verbascum thapsus, a widespread introduced species from Europe, contains rotenone in its leaves and seeds and has been used for fish poisoning.[where?]
^Pomar, L. 1901 An Account of the Fishing Industry in Chile, Pan American Exposition Publication IV, pub. Imprenta Moderna, Santiago. Page 33.
^Plowman, Timothy, Gyllenhaal, Lars Olof and Lindgren, Jan Erik "Latua pubiflora magic plant from southern Chile" Botanical Museum Leaflets Harvard University Vol. 23, No. 2, Cambridge, Massachusetts, November 12, 1971