According to Walker & Hasler (1949), trained bluntnose minnow, Hyborhynchus notatus (Pimephales notatus) are able to discriminate rinses of the following pairs of aquatic plants: Myriophyllum exalbescens and Ceratophyllum demersum, Ranunculus trichophyllus and Anacharis canadensis, Utricularia vulgaris and Vallisneria americana, Potamogeton zosteriformis and P. cripus, P. amplifolius and P. vaginatus as well as Chara excelsa and P. pectinatus. Of 12 plant species tested, only rinses with odors of C. demersum and A. canadensis resemble each other.

Figure 1. Bluntnose minnow, Pimephales notatus (powered by Joseph Tomelleri)

The threshold of chemosensitivity to odors of aquatic plants is at the level of 1:10000 dilution (Walker & Hasler, 1949), plus additional dilution in the test aquarium that demonstrates overall very high odor sensitivity.

Rinses of Cabomba caroliniana, Sparganium sp., Utricularia vulgaris, Nuphar variegatum and Potamogeton epihydris are attractive for migrating elvers of American eel, Anguilla rostrata (Sorensen, 1986). However, the attractivity of these rinses is exceptionally determined by epiphytic bacteria, fungi and algae that are abundant on the most species of aquatic plants.

Rinses of seaweeeds, Ascophyllum nodosum and Laminaria saccharina, repel elvers (Sorensen, 1986).

Finally, rinses of decaying leaf detritus are highly attractive to elvers regardless of where detritus is collected (Sorensen, 1986). In contrast, rinses of living and fallen leaves collected from the forest floor are not attractive.

Basic References

Sorensen P.W. 1986. Origins of the freshwater attractant(s) of migrating elvers of the American eel, Anguilla rostrata. Environmental Biology of Fishes 17, 185-200

Walker T.J., Hasler A.D. 1949. Detection and discrimination of odors of aquatic plants by the bluntnose minnow (Hyborhynchus notatus). Physilological Zoology 22, 45-63