Digestive enzyme pattern of two stomachless filter feeders, silver carp, Hypophthalmichthys molitrix Val., and bighead carp, Aristichthys nobilis Rich.

Abstract

Activities of digestive enzymes (trypsin and amylase) of microplanktophagous silver carp, Hypophthalmichthys molitrix, and macroplanktophagous bighead carp, Aristichthys nobilis, were investigated in relation to pH in 10 different segments of the gut. In addition, the possible existence of 'classical' lysozyme in both species and cellulase in silver carp were scrutinized, but no activities were detected. Tryptic and amylolytic activities decreased sharply from fore-gut to hind-gut indicating an efficient reabsorption mechanism. Trypsin and amylase of both species had a pH optimum at 8.3 and 7.0 respectively. The relatively low pH of 6.4 in the fore-gut of silver carp did not support an efficient operation of these enzymes, which was compensated by a higher enzyme concentration as compared to bighead carp. The latter, however, showed a higher pH of 7.3 in the fore-gut and thereby maintained similar activities as silver carp. The distinction of herbivorous and omnivorous fish in terms of digestion mechanisms is discussed.

Gut contents of silver carp, Hypophthalmichthys molitrix, and the disruption of a centric diatom, Cyclotella, on passage through the esophagus and intestine

“…Lazzaro, 1987 . Although phytoplankton are considered to be the major nutritional component of many filter-feeding fishes, the digestibility of algae has been a matter of debate for Ž decades, i.e., gut content comparison between fore-gut and hind-gut Ni and Chiang, . Ž 1954;Spataru, 1977;Bitterlich, 1985a and analysis of digestive enzyme Bitterlich, . 1985b,c show that it is rather difficult for silver carp to digest algae with cellulose cell wall, while studies by using isotope techniques indicates that this fish digests green Ž algae and cyanobacteria efficiently Iwata, 1976;Shi et al, 1976;Zhu, 1982;Zhu and .…”

“…However, in stomachless filter-feeding fishes such as silver carp, the pH of the gut fluids is usually ) 6. The lack of cellulase in the gut fluids also indicates that it is difficult for them to Ž breakdown cellulose cell walls by enzymatic digestion Ni and Chiang, 1954;Bitterlich, . 1985a .…”

Effect of various dietary fats supplementation on the liver glycogen, protein and digestive enzymes activities in striped murrel, Channa striatus

“…Similar studies on the glycogen content estimated by many authors [11][12][13][14][15]. Digestive enzyme pattern of two stomachless filter feeders, silver carp, Hypophthalmichthys molitrix Val., and bighead carp, Aristichthys nobilis has been reported [41]. Influence of Bacillus coagulans CC1 on growth performance and digestive enzyme activites of Catla catla had been reported [42].…”

Practical Success of Biomanipulation using Filter-Feeding Fish to Control Cyanobacteria Blooms: A Synthesis of Decades of Research and Application in a Subtropical Hypereutrophic Lake

“…In filter-feeding fish with no stomachs, such as silver carp, the pH of the gut fluids usually is >6. No cellulase in the gut of silver carp was found [26], and in vitro incubation of a filamentous cyanobacterium (Anabaena flos-aquae) with digestive juices of silver carp resulted in only 10% of the algal protein being hydrolyzed to free amino acids [24]. It was concluded that silver carp are omnivorous rather than herbivorous [25,26].…”