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The aim of the fish farmer is the efficient conversion of compounded diet into live fish, with the minimum of waste, and clearly any way of increasing the acceptability or palatability of fish diet would be advantageous. Fish vary considerably in their willingness to accept compounded diet. Salmonids in general readily accept fishmeal-based diets while Dover sole require the addition of scallop or Nephrows waste. This is due, in part at least, to the fact that salmonids are visual feeders while Dover sole use their chemical senses, smell and taste, in the detection of food.

To be acceptable, a diet must satisfy several criteria -

  1. Appearance: size, shape, colour

  2. Smell: which in the case of aquatic animals, should be termed long-range chemical attraction, since such animals can use both smell and taste to detect food at a distance.

  3. Feel: is the material hard or soft, most or dry, rough or smooth?

  4. Taste: taste buds in the mouth moniter the taste of the material.

Which are the most important features of a food depends on whether the particular fish is a visual or chemosensory feeder. The chemical activators can be divided into three groups. Attractants guide the fish towards the food, incitants invoke biting and tasting, and feeding stimulants induce the fish to swallow the food.

It is the nature of the gustatory feeding stimulants that has been studied at the Institute of Marine Biochemistry (IMB). The test diet was based on casein (Table 1) and the unflavoured diet was unacceptable to most fish. However, when a mixture of chemicals, based on an analysis of squid mantle tissue (synthetic squid mixture, Table 2) was added at a level of 1–2%, the fish readily ate the diet. The feeding stimulant could then be identified by adding various components of the complete mixture to the casein diet and measuring the quantity of test diet eaten.

Table 3 gives a summary of the results obtained at IMB and elsewhere, along with the major prey animals of the fish. Tabulation of the fish under Order and Family indicated that if there is any taxonomic relationship with the feeding stimulants it exists at or below the Family level.

Another possible factor in the “choice” of feeding stimulant is the feeding habits of the wild fish under natural conditions. Free L-amino acids, the feeding stimulants for sea bass (Mackie & Mitchell, 1982), European eel (Mackie & Mitchell, 1983) and Japanese eel (Takeda et al., 1984), are present in all animal tissues, both vertebrate and invertebrate. Different amino acid mixtures acted as feeding stimulants for the various species, and in all cases the corresponding D-amino acids were ineffective.

Inosine and inosine 5'-monophosphate are the specific feeding stimulants for the turbot (Mackie & Adron, 1978) and the brill (Mitchell, unpublished results), and the prey of juveniles and adults of both species all contain this chemical. Inosine 5'-monophosphate also as a feeding stimulant for juvenile yellowtail (Hosokawa et al., cited by Takeda et al., 1984).

The red sea bream, Dover sole and puffer eat worms, molluscs and Crustacea which all contain glycine betaine and free L-amino acids, the feeding stimulants. It is generally considered that teleost fish contain little or no glycine (Love, 1970), while invertebrates and elasmobranchs are rich in this chemical. However, Carr et al. (1977) has shown that in the pigfish, which eats small fish in addition to invertebrates, the feeding stimulant is again a mixture of glycine betaine plus free amino acids, and these authors also reported fairly high levels of glycine betaine in mullet tisuue.

A much wider range of fish species will have to be investigated before any definite conclusions can be drawn, and before any predictions can be made regarding the chemical nature of the feeding stimulant of an untested species. However, fish -eating species most probably have amino acid mixtures or inosine 5'-monophosphate as feeding stimulates and these eating invertebrates, glycine betaine plus amino acids.


Carr, W.E.S., Blumenthal, K.M. & Netherton, J.C. (1977). Chemoreception in the pigfish, Orthopristis chrysopterus : the contribution of amino acids and betaine to stimulation of feeding behaviour by various extracts. Comp. Biochem. Physiol. 58A, 69–73.

Goh, Y. & Tamura, T. (1980). Effect of amino acids on the feeding behaviour in red sea bream. Comp. Biochem. Physiol. 66C, 225–229.

Love, R.M. (1970). The Chemical Biology of Fishes. Academic Press, London and New York.

Mackie, A.M. (1982). Identification of the gustatory feeding stimulants. In “Chemorecption in Fishes” (T.J. Hara, ed.), 275–291. Elsevier Scientific Publishing Co., Amsterdam.

Mackie, A.M. & Adron, J.W. (1978). Identification of inosine and inosine 5'-monophosphate as the gustatory feeding stimulants for the turbot, Scophthalmus maximus. Comp. Biochem. Physiol. 60A, 79–83.

Mackie, A.M. Adron, J.w. & Grant, P.T. (1980). Chemical nature of feeding stimulants for the juvenile Dover sole, Solea solea (L.). J. Fish. Biol. 16, 701–708.

Mackie, A.M. & Mitchell, A.I. (1982). Chemical ecology and chemoreception in the marine environment. In “Indices Biochimique et milieux marins” (Journees du GABIN, Brest, 18–20 Nov. 1981). Publ. CMEXO (Actes Collon. ) 14, 11–24.

Mackie, A.M. & Mitchell, A.I. (1983). Studies on the chemical nature of feeding stimulants for the juvenile European eel, Anguilla anguilia (L.). J. Fish Biol. 22, 425–430.

Ohsugi, T., Hidaka, I. & Ikeda, M. (1978). Taste receptor stimulation and feeding behaviour in the puffer, Fugu pardalis. II. Effects produced by mixtures of constituents of clam extracts. Chem. Senses Flavour 3, 355–368.

Takeda, M., Takii, K. & Matsui, K. (1984). Identification of feeding stimulants for juvenile eel. Bull. Jap. Soc. Scient. Fish. 50. 645–651.

Table 1. Composition de la nourriture d'essai

(Composition of test diet)

 g/2 Kg
Caséine (sans vitamines)
(vitamin-free casein)
huile de poisson
(fish oil)
agglomérant (CM-cellulose, Na)
mélange des vitamines
(vitamin mixture)
mélange des mineraux
(mineral mixture)
matière colorante (Sunset Yellow)
(food colour)

100 g nourriture sec mélangé avec 160 ml solution aqueuse
(100 g dry diet mixed with 160 ml aqueous solution)

Table 2. Composition of du mélange “Synthetic squid”

(composition of synthetic squid mixture)

% composition
L-aspartic acid0.31L-proline24.69
L-glutamic acid0.89L-arginine3.84
L-isoleucine0.49glycine betaine HCL15.34
L-leucine0.92trimethylamine HCL19.17
L-tyrosine0.37trimethylamine HCL1.53
L-lysine HCL0.49inosine0.43
L-histidine HCL0.24adenosine 5' -monophosphate0.67
taurine5.67L-(+)-lactic acid1.53

Basésur l'analyse de la chair de l'encornet, Loligo forbesi(Mackie, 1973).

Mélange dissous dans l'eau distillé et pH adjustée à 6.5.

Table 3. Survey of food organisms and feeding stimulants

Anguille européene, Anguilla anguilla
Crustacés, mollusques, vers, poissonsMélange des acides aminés de serie L
(Mackie & Mitchell, 1983)
Anguille japonaise, A. japonica
Crustacés, mollusques, vers poissonsMélange des acides aminés de serie L
(Takeda et al., 1984)
Famille Serranidae
Bar, Dicentrarchus labrax
Juvéniles: crustacés, poissons
Adults: poissons
Mélange des acides aminés de series L
(Mackie & Mitchell, 1982)
Famille Carangidae
Seriollc, Seriola quinqueradiata
Juvéniles: cephalopods, poissonsInosine 5' -monophosphate (avec les acides aminés).
(Hosokawa et al., cité par Takeda et al., 19
Famille Pomadasyidae
Orthopristis chrysopterus
Juvertebrés divers, poissonsGlycine betaine avec les acides aminés
(Carr et al., 1977)
Famillie Sparidae
Daurade royale, Chrysophyrs major
Crustacés, versGlycine betaine avec les acides aminés
(Coh & Faura, 1980)
Famille Bothidae
Turbot, Scohthalmus maximus
Juvéniles: mollusques, vers
Adulsts: poissons
Inosine ou 5'-monophosphate
(Mackie & Adron, 1978)
Barbue, S. rhombus
Juvéniles: mollusques, vers
Adulsts: poissons, cephalopods,
Inosine ou inosine 5'-monophosphate
(Mitchell, oeuvre non publié)
Famille Pleuronectidae
Plie, Pleuronectes platessa
Vers, mollusques, crustacesMélange complex des produits chimiques
(Mackie, 1982)
Famille Soleidae
Sole, Solea solea
Vers, mollusques, crustacesGlycine betaine aves les acides aminés
(Mackie et al., 1980)
Fugu pardalis
Vers, mollusques, crustacesGlycine betaine aves les acides aminés
(Ohsugi et al., 1978)

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