Spinefoot rabbitfish, Siganus rivulatus, is an economically important species of herbivorous fish... more Spinefoot rabbitfish, Siganus rivulatus, is an economically important species of herbivorous fish that is relatively easy to rear and thus considered to be suitable for aquaculture. Juveniles are generally reared in nursery systems before being stocked into growout cages or ponds. We report here our evaluation of the effects of stocking density on the survival, growth, feed efficiency and condition index of S. rivulatus juveniles in nursery tanks. The experiment was conducted in a recirculating system of twelve 52-l aquaria connected to a biological filter and a sand filter. Juvenile fish (average weight 6.5 g) were stocked into aquaria at four stocking densities (10, 20, 30, and 40 fish/aquarium) with three replicate aquaria per treatment. Diet was provided at 3% body weight daily divided into two feedings. Fish were weighed weekly for 8 weeks and the diet increased accordingly. Survival was greater than 95% in all treatments, with no significant differences observed among treatments. There were also no differences in specific growth rate (SGR 2.12–2.27) of the fish among treatments. Growth rate was linear during the 8 weeks in all treatments, and harvested biomass increased proportionally to stocking density (198, 401, 600 and 785 g per increasing stocking density, respectively). Feed efficiency (FE 0.67–0.71) of the fish did not vary significantly among treatments. The coefficient of variation was high (35–41%) among the harvested fish, but it also did not differ significantly among treatments. The final condition indices of the fish in all treatments were similar to each other but significantly greater than the initial values (P\0.05). The results suggest that there is no apparent effect of stocking density at the levels tested on the survival and growth of juvenile rabbitfish.
The use of prebiotics and probiotics as feed supplements that
improve efficiency of intestinal ba... more The use of prebiotics and probiotics as feed supplements that improve efficiency of intestinal bacteria is becoming de rigueur in animal husbandry in many regions worldwide. We tested the effects of a commercial probiotic (Biogen) containing allicin, high unit hydrolytic enzyme, Bacillus subtilis spores and ginseng extracts on survival, growth, carcass composition and feed cost/benefit in rabbitfish Siganus rivulatus. Fifteen net cages (100 · 100 · 40 cm; L · W · H) were stocked with 10 juvenile rabbitfish (10.3 g per fish) each and placed in a large rectangular tank and offered feed at 4% body weight daily. Cages were offered one of five isonitrogenous and isocaloric diets containing 0, 1, 2, 3 and 4 g kg)1 probiotic at three replicates per treatment for 98 days. Fish in all cages were weighed at 2-week intervals and feed regimen was adjusted accordingly. Rabbitfish offered the control diet exhibited lower growth and feed utilization than all experimental treatments. There was no effect of probiotic inclusion level on survival but growth was better at all inclusion levels than in the control. No significant differences (P > 0.05) in growth were observed among fish groups fed various levels of the probiotic. Carcass composition was not affected by dietary probiotic inclusion. Ultimately, when all variables are considered, Biogen inclusion to diets appears to reduce feed cost per unit growth of rabbitfish.
Rabbitfish (Siganidae) are an Indo-Pacific family of teleosts considered very suitable for aquacu... more Rabbitfish (Siganidae) are an Indo-Pacific family of teleosts considered very suitable for aquaculture. The rabbitfish Siganus rivulatus has established populations in the Eastern Mediterranean and in now part of the commercial fishery in some Mediterranean countries. In the present work, we studied the salinity tolerance of S. rivulatus and the effect of various salinities on plasma osmolality and gill Na+–K+–ATPase activity (NKA). Three salinity experiments were performed. In the first experiment, fish were maintained at nine salinities between 10 ppt and 50 ppt for 3 weeks and survival and plasma osmolality evaluated. In the second experiment fish were maintained at salinities of 25, 30, 35 and 40 ppt for 6 weeks to study survival, growth, blood osmolality and gill NKA. In the third experiment, fish were maintained at salinities of 10, 15, 20 and 25 ppt for 8 weeks and again survival, growth, blood osmolality and gill NKA were estimated. Results of the first experiment show that S. rivulatus can survive for 3 weeks at salinities ranging from 10 ppt to 50 ppt and that they can maintain a relatively stable blood osmolality (between 398 and 435 mmol kg−1). In the second experiment we observed no differences in survival and growth of S. rivulatus in all treatments. However, gill NKA was lowest at 35 ppt and increased at salinities above and below 35 ppt. In the third experiment, survival was similar at all salinity treatments but growth decreased slightly at 10 ppt. Gill NKA increased as salinity decreased. Results show that S. rivulatus is a highly euryhaline fish and a very strong osmoregulator. Furthermore, although iso-osmolality is at 14.6 ppt, NKA activity is lowest at 35 ppt, which is the salinity in the Indo-Pacific where the fish evolved but not in the Mediterranean where juveniles for the present experiment were collected. Thus, we conclude that 35 ppt is the optimum salinity for S. rivulatus.
International Journal of Food Science and Technology, 2008
Fish are a good nutritional source of proteins, essential fatty acids and minerals. Societies wit... more Fish are a good nutritional source of proteins, essential fatty acids and minerals. Societies with high fish intake have lower rates of acute myocardial infarctions and atherosclerosis, better cognitive functions, and better neural and visual development in foetuses. In the present work, we evaluated seasonal variation in proximate composition of two commercial fish species, the rabbitfish Siganus rivulatus, an algaevore, and the white sea bream Diplodus sargus, a carnivore from the eastern Mediterranean. Fifteen fish were collected on the second weekend of each of 8 months covering the four seasons. Results show that the nutritive value of a species of fish varies throughout the year. Furthermore, rabbitfish tissue generally contains more lipids than white sea bream, and fillet yield from rabbitfish is greater than from sea bream. As both fish are sold at a similar price in Lebanese markets, results suggest that rabbitfish offers better value for the price than does white sea bream.
Spinefoot rabbitfish, Siganus rivulatus, is an economically important species of herbivorous fish... more Spinefoot rabbitfish, Siganus rivulatus, is an economically important species of herbivorous fish that is relatively easy to rear and thus considered to be suitable for aquaculture. Juveniles are generally reared in nursery systems before being stocked into growout cages or ponds. We report here our evaluation of the effects of stocking density on the survival, growth, feed efficiency and condition index of S. rivulatus juveniles in nursery tanks. The experiment was conducted in a recirculating system of twelve 52-l aquaria connected to a biological filter and a sand filter. Juvenile fish (average weight 6.5 g) were stocked into aquaria at four stocking densities (10, 20, 30, and 40 fish/aquarium) with three replicate aquaria per treatment. Diet was provided at 3% body weight daily divided into two feedings. Fish were weighed weekly for 8 weeks and the diet increased accordingly. Survival was greater than 95% in all treatments, with no significant differences observed among treatments. There were also no differences in specific growth rate (SGR 2.12–2.27) of the fish among treatments. Growth rate was linear during the 8 weeks in all treatments, and harvested biomass increased proportionally to stocking density (198, 401, 600 and 785 g per increasing stocking density, respectively). Feed efficiency (FE 0.67–0.71) of the fish did not vary significantly among treatments. The coefficient of variation was high (35–41%) among the harvested fish, but it also did not differ significantly among treatments. The final condition indices of the fish in all treatments were similar to each other but significantly greater than the initial values (P\0.05). The results suggest that there is no apparent effect of stocking density at the levels tested on the survival and growth of juvenile rabbitfish.
The use of prebiotics and probiotics as feed supplements that
improve efficiency of intestinal ba... more The use of prebiotics and probiotics as feed supplements that improve efficiency of intestinal bacteria is becoming de rigueur in animal husbandry in many regions worldwide. We tested the effects of a commercial probiotic (Biogen) containing allicin, high unit hydrolytic enzyme, Bacillus subtilis spores and ginseng extracts on survival, growth, carcass composition and feed cost/benefit in rabbitfish Siganus rivulatus. Fifteen net cages (100 · 100 · 40 cm; L · W · H) were stocked with 10 juvenile rabbitfish (10.3 g per fish) each and placed in a large rectangular tank and offered feed at 4% body weight daily. Cages were offered one of five isonitrogenous and isocaloric diets containing 0, 1, 2, 3 and 4 g kg)1 probiotic at three replicates per treatment for 98 days. Fish in all cages were weighed at 2-week intervals and feed regimen was adjusted accordingly. Rabbitfish offered the control diet exhibited lower growth and feed utilization than all experimental treatments. There was no effect of probiotic inclusion level on survival but growth was better at all inclusion levels than in the control. No significant differences (P > 0.05) in growth were observed among fish groups fed various levels of the probiotic. Carcass composition was not affected by dietary probiotic inclusion. Ultimately, when all variables are considered, Biogen inclusion to diets appears to reduce feed cost per unit growth of rabbitfish.
Rabbitfish (Siganidae) are an Indo-Pacific family of teleosts considered very suitable for aquacu... more Rabbitfish (Siganidae) are an Indo-Pacific family of teleosts considered very suitable for aquaculture. The rabbitfish Siganus rivulatus has established populations in the Eastern Mediterranean and in now part of the commercial fishery in some Mediterranean countries. In the present work, we studied the salinity tolerance of S. rivulatus and the effect of various salinities on plasma osmolality and gill Na+–K+–ATPase activity (NKA). Three salinity experiments were performed. In the first experiment, fish were maintained at nine salinities between 10 ppt and 50 ppt for 3 weeks and survival and plasma osmolality evaluated. In the second experiment fish were maintained at salinities of 25, 30, 35 and 40 ppt for 6 weeks to study survival, growth, blood osmolality and gill NKA. In the third experiment, fish were maintained at salinities of 10, 15, 20 and 25 ppt for 8 weeks and again survival, growth, blood osmolality and gill NKA were estimated. Results of the first experiment show that S. rivulatus can survive for 3 weeks at salinities ranging from 10 ppt to 50 ppt and that they can maintain a relatively stable blood osmolality (between 398 and 435 mmol kg−1). In the second experiment we observed no differences in survival and growth of S. rivulatus in all treatments. However, gill NKA was lowest at 35 ppt and increased at salinities above and below 35 ppt. In the third experiment, survival was similar at all salinity treatments but growth decreased slightly at 10 ppt. Gill NKA increased as salinity decreased. Results show that S. rivulatus is a highly euryhaline fish and a very strong osmoregulator. Furthermore, although iso-osmolality is at 14.6 ppt, NKA activity is lowest at 35 ppt, which is the salinity in the Indo-Pacific where the fish evolved but not in the Mediterranean where juveniles for the present experiment were collected. Thus, we conclude that 35 ppt is the optimum salinity for S. rivulatus.
International Journal of Food Science and Technology, 2008
Fish are a good nutritional source of proteins, essential fatty acids and minerals. Societies wit... more Fish are a good nutritional source of proteins, essential fatty acids and minerals. Societies with high fish intake have lower rates of acute myocardial infarctions and atherosclerosis, better cognitive functions, and better neural and visual development in foetuses. In the present work, we evaluated seasonal variation in proximate composition of two commercial fish species, the rabbitfish Siganus rivulatus, an algaevore, and the white sea bream Diplodus sargus, a carnivore from the eastern Mediterranean. Fifteen fish were collected on the second weekend of each of 8 months covering the four seasons. Results show that the nutritive value of a species of fish varies throughout the year. Furthermore, rabbitfish tissue generally contains more lipids than white sea bream, and fillet yield from rabbitfish is greater than from sea bream. As both fish are sold at a similar price in Lebanese markets, results suggest that rabbitfish offers better value for the price than does white sea bream.
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Papers by Imad Saoud
improve efficiency of intestinal bacteria is becoming de rigueur
in animal husbandry in many regions worldwide. We
tested the effects of a commercial probiotic (Biogen) containing
allicin, high unit hydrolytic enzyme, Bacillus subtilis
spores and ginseng extracts on survival, growth, carcass
composition and feed cost/benefit in rabbitfish Siganus rivulatus.
Fifteen net cages (100 · 100 · 40 cm; L · W · H)
were stocked with 10 juvenile rabbitfish (10.3 g per fish) each
and placed in a large rectangular tank and offered feed at 4%
body weight daily. Cages were offered one of five isonitrogenous
and isocaloric diets containing 0, 1, 2, 3 and 4 g kg)1
probiotic at three replicates per treatment for 98 days. Fish
in all cages were weighed at 2-week intervals and feed regimen
was adjusted accordingly. Rabbitfish offered the control
diet exhibited lower growth and feed utilization than all
experimental treatments. There was no effect of probiotic
inclusion level on survival but growth was better at all
inclusion levels than in the control. No significant differences
(P > 0.05) in growth were observed among fish groups fed
various levels of the probiotic. Carcass composition was not
affected by dietary probiotic inclusion. Ultimately, when all
variables are considered, Biogen inclusion to diets appears
to reduce feed cost per unit growth of rabbitfish.
rivulatus has established populations in the Eastern Mediterranean and in now part of the commercial fishery in some
Mediterranean countries. In the present work, we studied the salinity tolerance of S. rivulatus and the effect of various salinities on
plasma osmolality and gill Na+–K+–ATPase activity (NKA). Three salinity experiments were performed. In the first experiment,
fish were maintained at nine salinities between 10 ppt and 50 ppt for 3 weeks and survival and plasma osmolality evaluated. In the
second experiment fish were maintained at salinities of 25, 30, 35 and 40 ppt for 6 weeks to study survival, growth, blood
osmolality and gill NKA. In the third experiment, fish were maintained at salinities of 10, 15, 20 and 25 ppt for 8 weeks and again
survival, growth, blood osmolality and gill NKA were estimated. Results of the first experiment show that S. rivulatus can survive
for 3 weeks at salinities ranging from 10 ppt to 50 ppt and that they can maintain a relatively stable blood osmolality (between 398
and 435 mmol kg−1). In the second experiment we observed no differences in survival and growth of S. rivulatus in all treatments.
However, gill NKA was lowest at 35 ppt and increased at salinities above and below 35 ppt. In the third experiment, survival was
similar at all salinity treatments but growth decreased slightly at 10 ppt. Gill NKA increased as salinity decreased. Results show
that S. rivulatus is a highly euryhaline fish and a very strong osmoregulator. Furthermore, although iso-osmolality is at 14.6 ppt,
NKA activity is lowest at 35 ppt, which is the salinity in the Indo-Pacific where the fish evolved but not in the Mediterranean where
juveniles for the present experiment were collected. Thus, we conclude that 35 ppt is the optimum salinity for S. rivulatus.
improve efficiency of intestinal bacteria is becoming de rigueur
in animal husbandry in many regions worldwide. We
tested the effects of a commercial probiotic (Biogen) containing
allicin, high unit hydrolytic enzyme, Bacillus subtilis
spores and ginseng extracts on survival, growth, carcass
composition and feed cost/benefit in rabbitfish Siganus rivulatus.
Fifteen net cages (100 · 100 · 40 cm; L · W · H)
were stocked with 10 juvenile rabbitfish (10.3 g per fish) each
and placed in a large rectangular tank and offered feed at 4%
body weight daily. Cages were offered one of five isonitrogenous
and isocaloric diets containing 0, 1, 2, 3 and 4 g kg)1
probiotic at three replicates per treatment for 98 days. Fish
in all cages were weighed at 2-week intervals and feed regimen
was adjusted accordingly. Rabbitfish offered the control
diet exhibited lower growth and feed utilization than all
experimental treatments. There was no effect of probiotic
inclusion level on survival but growth was better at all
inclusion levels than in the control. No significant differences
(P > 0.05) in growth were observed among fish groups fed
various levels of the probiotic. Carcass composition was not
affected by dietary probiotic inclusion. Ultimately, when all
variables are considered, Biogen inclusion to diets appears
to reduce feed cost per unit growth of rabbitfish.
rivulatus has established populations in the Eastern Mediterranean and in now part of the commercial fishery in some
Mediterranean countries. In the present work, we studied the salinity tolerance of S. rivulatus and the effect of various salinities on
plasma osmolality and gill Na+–K+–ATPase activity (NKA). Three salinity experiments were performed. In the first experiment,
fish were maintained at nine salinities between 10 ppt and 50 ppt for 3 weeks and survival and plasma osmolality evaluated. In the
second experiment fish were maintained at salinities of 25, 30, 35 and 40 ppt for 6 weeks to study survival, growth, blood
osmolality and gill NKA. In the third experiment, fish were maintained at salinities of 10, 15, 20 and 25 ppt for 8 weeks and again
survival, growth, blood osmolality and gill NKA were estimated. Results of the first experiment show that S. rivulatus can survive
for 3 weeks at salinities ranging from 10 ppt to 50 ppt and that they can maintain a relatively stable blood osmolality (between 398
and 435 mmol kg−1). In the second experiment we observed no differences in survival and growth of S. rivulatus in all treatments.
However, gill NKA was lowest at 35 ppt and increased at salinities above and below 35 ppt. In the third experiment, survival was
similar at all salinity treatments but growth decreased slightly at 10 ppt. Gill NKA increased as salinity decreased. Results show
that S. rivulatus is a highly euryhaline fish and a very strong osmoregulator. Furthermore, although iso-osmolality is at 14.6 ppt,
NKA activity is lowest at 35 ppt, which is the salinity in the Indo-Pacific where the fish evolved but not in the Mediterranean where
juveniles for the present experiment were collected. Thus, we conclude that 35 ppt is the optimum salinity for S. rivulatus.