Gustatory sensitivity of the herbivore Tilapia zillii to amino acids

Abstract

The gustatory sensitivity of the herbivorous fish Tilapiu zilliiwas investigated using electrophysiological techniques. Integrated responses from facial taste nerves were recorded duringstimulation by I I amino acids. All compoundsproved to be effective stimuli. The relative stirnulatory efficacy (RSE) determined at 1 x 10 M indicated that stimuli can be organized into three groups on the basis of similarity of efficacy. Effects of pH which altered the RSE of some amino acids are documented. Amino acid RSE differed to some extent from those of previously studied carnivorous fish. There was concordance between the composition of preferred food, effective feeding stimuli and the peripheral receptor responses. These observations support the hypothesis that peripheral chemosensitivity might serve as a mechanism of feeding specialization in some fish.

Gustatory responses to feeding‐ and non‐feeding‐stimulant chemicals, with an emphasis on amino acids, in rainbow trout

“…Channel catfish (Caprio, 1978), Japanese minnow Pseudorasbora parva (Temmnick & Schlegel)(Kaku et al ., 1980; Kiyohara et al ., 1981), tilapia Tilapia zillii (Gerrais)(Johnsen et al ., 1990) and several marine fishes (Goh & Tamura, 1980; Hidaka & Ishida, 1985; Ishida & Hidaka, 1987) constitute the ‘wide response range’ group, in which the gustatory system generally responds to a number of neutral, basic and acidic amino acids. Therefore, in theses species the stimulatory amino acid spectrum of the gustatory system largely overlaps with that of the olfactory.…”

“…Carp Cyprinus carpio L., unlike goldfish, exhibit response characteristics for amino acids similar to those of the channel catfish (Marui et al, 1983(Marui et al, , 1987. Herbivorous tilapia are characterized by their higher sensitivity to Arg and Glu than Pro and neutral amino acids (Johnsen et al, 1990). All marine species examined are generally less sensitive to amino acids relative to freshwater species, showing the greatest sensitivity to Pro, with strong responses to Gly (Ishida & Hidaka, 1987).…”

The diversity of chemical stimulation in fish olfaction and gustation

“…A cyprinid, Pseudorasbora parva, shows similar response characteristics to that of channel catfish (Kiyohara et al, 1981). A herbivore (Tilapia zillii, Cichlidae) and seven marine species respond to all three types of amino acids (Goh and Tamura, 1980;Hidaka and Ishida, 1985;Ishida and Hidaka, 1987;Johnsen et al, 1990).…”

Mouth and Sense Organs

“…If the species feeds by visual stimuli, sight will outweigh the chemical senses in detect- Johnsen et al (1990). If the species feeds by visual stimuli, sight will outweigh the chemical senses in detect- Johnsen et al (1990).…”