Two groups of juvenile grass carp Ctenopharyngodon idella have been raised within 6 months on animal and vegetable foods (Kasumyan & Morsi, 1997). Carps conditionally named carnivorous have been grown on Chironomidae larvae, carps named vegetarian  on duckweed and Romaine lettuce (Lactuca sativa) leaves, respectively. After conditioning, carnivorous carps show preferences for agar-agar pellets with the Chironomidae larvae extract (75 g w.w. per 1 liter), vegetarian carps  to pellets with the lettuce extract (75 g w.w.). According to Kasumyan & Morsi (1997), carps of both groups do not change specific preferences for individual 21 amino acids and 4 classical taste substances tested.

Generally, gustatory search images form in the memory of fish relatively quickly. In common carp, Cyprinus carpio (Ivlev, 1977), fairly stable visual and gustatory search images in respect of Chironomidae larvae and other natural foods form within 1-2 weeks.

Basic References

Ivlev V.S. 1977. Experimental ecology of the feeding of fishes. Nukova Dumka Publishers, Kyiv

Kasumyan A.O., Morsi A.M.K. 1997. Taste preferences of classical taste substances by juvenile grass carp Ctenopharyngodon idella (Cyprinidae, Pisces), raised on animal and vegetate foods. Proceedings of the Russian Academy of Sciences 357, 284-286

Attraction potentials of sugars and related compounds have been statistically estimated in an olfactometer on the basis of exploratory and feeding behavior in oriental weatherfish, Misgurnus anguillicaudatus (Harada et al., 1994). Six monosaccharides, three disaccharides, six sugar alcohols, six glycosides and two artificial sweeteners have been tested. Among them, fructose, glycyrrhizin, aspartame and rebaudioside, especially the last, show the higher attractivity. Using the same technique, Harada et al. (1995) have studied the attractivity of the foregoing sugars and related compounds for yellowtail, Seriola quinqueradiata, discovering that galactose, maltose and glycyrrhizin are highly attractive for this fish.

Somewhat earlier, Rottiers & Lemm (1985) have found that juvenile walleyes, Stizostedion vitreum, are attracted by sucrose solution in the Y-shaped olfactometer.

It is important to underline that olfactory responses of fish do not correlate with their gustatory, first of all intraoral responses to the same substanses (Kasumyan & Døving, 2003; Hara, 2006). In carp, Cyprinus carpio, for example, amino acids (alanine, valine and leucine) most attractive in the olfactometer experiments (Saglio et al., 1990) are not matched with amino acids (cysteine, proline, glutamic and aspartic acids) most attractive as ingredients in the palatable agar-agar pellets (Kasumyan & Morsi, 1996; see also Wood & Azócar, 2013).

Sucrosa is an indifferent gustatory stimulus for carp (Kasumyan & Morsi, 1996).

According to Kasumyan & Døving (2003) and Isaeva (2007), sucrosa as gustatory stimulus is also indifferent for many other cyprinid (Cyprinidae) fish such as tench Tinca tinca, bitterling Rhodeus sericeus amarus, lake bleak Leucaspius delineatus, crucian Carassius carassius, goldfish Carassius auratus, chub Leuciscus cephalus, European minnow Phoxinus phoxinus and bream Abramis brama, in the experiments with the agar-agar pellets. Sucrosa as gustatory stimulus is only positive for roach Rurilus rutilus, grass carp Ctenopharyngodon idella as well as for guppy Poecilia reticulata (Poeciliidae) (Kasumyan & Døving, 2003) which eat the most large amount of vegetable food.

According to Chervova & Lapshin (2005), external parts of the head in C. carpio (such as the center of the upper lip) is less sensitive (3 orders of magnitude) to saccharosa than to cysteine.

Basic References

Chervova L.S., Lapshin D.N. 2005. The threshold sensitivity of external chemoreceptor in carp Cyprinus carpio to amino acids and classical gustatory substances. Journal of Ichthyology 45, S307-S314

Hara T.J. 2006. Feeding behaviour in some teleosts is triggered by single amino acids primarily through olfaction. Journal of Fish Biology 68, 810-825

Harada K., Miyasaki T., Tamura Y. 1994. Attractivity of sugars and related compounds for the oriental weatherfish Misgurnus anguillicaudatus. Fisheries Science 60, 643-645

Harada K., Miyasaki T., Tamura Y. 1995. Attraction of yellowtail, Seriola quinqueradiata for sugars and related compounds. Aquaculture Science 43, 51-55

Isaeva O.M. 2007. Taste preferences and taste behaviour of cyprinid fish. Moscow Lomonosov State University ... Read more »