Question
I RECENTLY HAD A WATER POND PUT IN WHICH IS LOCATED UNDER A BLACKWALNUT TREE. ASKED CONTRACTOR IF WALNUT WOULD BE OK AROUND POND HE SAID YES. WHEN TRANSFERRING MY FISH TO POND THEY ALL DIED WITHIN A MATTER OF MINUTES. COULD THE BLACK WALNUT TREE DRIPINGS HAD ANYTHING TO DO WITH IT? PLEASE HELP I LOST 27 FISH WHICH I HAVE SOME FOR ABOUNT 8 YEARS.

THANK YOU

Answer
Yes walnut hulls were used by indians to kill fish long ago . They contain a chemical called jugalone.

Jugalone Toxin

A handful of green hulls thrown into a pond or a lake has been known to kill the majority of the fish inhabitants. Crush the husks of "green" black walnuts and sprinkle them into sluggish water or ponds for use as fish poison. The toxins are so powerful that tomatoes, apples, and some other species cannot grow near large black walnut trees.


A.K.A. Eastern Walnut and American Walnut. The husk, shell and peel are sudorific, especially if used when the Walnuts are green. The green husks of the fruit, boiled, make a good yellow dye.

Black walnut (Juglans nigra) contains juglone. There have been no reports of toxicity in HUMANS from ingestion of parts of this tree. Ingestion of parts of the black walnut has caused toxicity in horses. Moldy walnuts have caused serious toxicity in dogs and are potentially toxic to birds. The juglone toxin occurs in the leaves, bark and wood of walnut, but these contain lower concentrations than in the roots. Juglone has experimentally been shown to be a respiration inhibitor which deprives sensitive plants of needed energy for metabolic activity. The largest concentrations of juglone and hydrojuglone (converted to juglone by sensitive plants) occur in the walnut's buds, nut hulls, and roots.

Poisoning was generally done in stagnant pools or slow-flowing streams and rivers, but has also been used by Californian Indians in saltwater environments for octopus and low-tide shellfish fishing (Heizer, 1953), as well as for catching fish trapped in inter-tidal pools (Bearez, 1998). Poisoning was such an effective method of harvesting fish that it was not uncommon for groups in some areas to purposefully dam small streams and ponds for this express purpose. Reducing water flow ensured that small quantities of the poison worked at maximum efficiency by minimizing dilution. In cases where the poison was not entirely effective, such as a restricted supply of poison or where stream flow diluted the strength of the poison, fishermen with scooping baskets, spears, or bow and arrows aided in capturing fish that were not fully drugged.