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Fishes, Volume 2, Issue 1 (March 2017) – 4 articles

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Article
Partial Characterization of Digestive Proteases in the Green Cichlid, Cichlasoma beani
Fishes 2017, 2(1), 4; https://doi.org/10.3390/fishes2010004 - 08 Mar 2017
Cited by 10 | Viewed by 1879
Abstract
This study undertakes the characterization of digestive proteases in the juvenile green cichlid, Cichlasoma beani. The results obtained showed a higher activity of alkaline proteases (0.14 ± 0.01 U mg protein−1) compared to acid proteases (0.07 ± 0.01 U mg protein [...] Read more.
This study undertakes the characterization of digestive proteases in the juvenile green cichlid, Cichlasoma beani. The results obtained showed a higher activity of alkaline proteases (0.14 ± 0.01 U mg protein−1) compared to acid proteases (0.07 ± 0.01 U mg protein−1) in this species. The optimum temperature of the alkaline proteases was 65 °C and these enzymes were more thermostable to temperature changes than the acid proteases, characterized by an optimal temperature of 55 °C. The pH optimum was 2 for acid proteases, and 11 for alkaline proteases, which were also more stable to changes in pH between 8 and 10. The use of specific inhibitors showed an acid protease inhibition of 88% with pepstatin A as inhibitor. In the zymogram SDS-PAGE analysis of alkaline proteases, five active fractions were revealed, indicating the presence of serine proteases. These results confirm that both alkaline and acid proteases are involved in the digestion of C. beani, and suggest that this species is omnivorous with carnivorous tendencies. The present study contributes to our knowledge about the digestive physiology of C. beani, and can be applied towards improved understanding of the kinds of protein sources that could be used in the development of inerts diets. Full article
(This article belongs to the Special Issue Nutritional Requirements in New Fish Species Under Culture)
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Article
Use of Potato Starch in Diets of Tropical Gar (Atractosteus tropicus, Gill 1863) Larvae
Fishes 2017, 2(1), 3; https://doi.org/10.3390/fishes2010003 - 07 Mar 2017
Cited by 11 | Viewed by 2085
Abstract
Tropical gar, Atractosteus tropicus, is a carnivorous fish species from Southern México with high value and acceptance in local markets. Therefore, the present study aims to spare proteins in diets for larviculture of this species. An experiment was performed using three different [...] Read more.
Tropical gar, Atractosteus tropicus, is a carnivorous fish species from Southern México with high value and acceptance in local markets. Therefore, the present study aims to spare proteins in diets for larviculture of this species. An experiment was performed using three different experimental diets with increasing carbohydrate levels based on potato starch (S) and decreasing protein content (P) and total energy: 16% S (16% S–44% P), 22% S (22% S–40% P) and 28% S (28% S–36% P). Tropical gar larvae (five days post-hatching, 2.1 mm average notochordal length) were assessed for growth, survival, degree of cannibalism, and digestive enzyme activities for 30 days. Highest growth and survival (24%), as well as the lowest cannibalism (33%), was seen in larvae fed the 28% S diet, and these larvae also had the highest lipase, amylase and glucosidase activities (0.28, 0.56 and 0.11 units, respectively). Protease activity (alkaline protease, trypsin, chymotrypsin, and leucine aminopeptidase) was higher in the larvae fed the 22% S diet than in those given the 16% S and 28% S diets. In conclusion, dietary inclusion of potato starch at 28% S enhanced growth, survival and some digestive enzyme activities, and decreased cannibalism in the larval gar. Potato starch could replace dietary protein as a major source of energy for A. tropicus larvae, thereby reducing the cost of diets. Full article
(This article belongs to the Special Issue Nutritional Requirements in New Fish Species Under Culture)
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Article
Utilization of Scatterplot Smoothers to Understand the Environmental Preference of Bigeye Tuna in the Southern Waters off Java-Bali: Satellite Remote Sensing Approach
Fishes 2017, 2(1), 2; https://doi.org/10.3390/fishes2010002 - 09 Feb 2017
Cited by 4 | Viewed by 1919
Abstract
The southern waters off Java-Bali were recognized as spawning and potential fishing ground for tuna species. However, few studies have been conducted on this area. In this paper, the environmental preference of bigeye tuna was assessed based on catch data and three main [...] Read more.
The southern waters off Java-Bali were recognized as spawning and potential fishing ground for tuna species. However, few studies have been conducted on this area. In this paper, the environmental preference of bigeye tuna was assessed based on catch data and three main environmental satellite data; namely; sea surface temperature (SST), sea surface chlorophyll (SSC), and sea surface height deviation (SSHD). Then, the relationship between bigeye tuna catches and environmental satellite data was analyzed by using a simplified method of the Generalized Additive Model (GAM) which is called scatterplot smoothers. This method is the forerunner of GAM and has not yet been applied for fisheries analysis. The aim of this study was to evaluate its performance for/in analyzing bigeye tuna habitat preference. The result indicated that SST, SSC, and SSHD had a high correlation with the bigeye tuna’s spatial patterns. Furthermore, spatial patterns of bigeye tuna preference display typical characteristics of low SST, low SSC, and low positive SSHD as well as areas with extreme SSHD values, which are almost the same results as those identified with GAM analysis in the same study area. Full article
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Article
Effect of Feed Protein:Lipid Ratio on Growth Parameters of African Catfish Clarias gariepinus after Fish Meal Substitution in the Diet with Bambaranut (Voandzeia subterranea) Meal and Soybean (Glycine max) Meal
Fishes 2017, 2(1), 1; https://doi.org/10.3390/fishes2010001 - 30 Jan 2017
Cited by 11 | Viewed by 3045
Abstract
Fishmeal (FM) was substituted with soybean meal (Glycine max) (SBM) and bambaranut meal (Voandzeia subterranea) (BNM) in 10 experimental African catfish, Clarias gariepinus, diets. Feed formulation was designed using mixture model. The inclusion level of the three protein ingredients varied between 0% and [...] Read more.
Fishmeal (FM) was substituted with soybean meal (Glycine max) (SBM) and bambaranut meal (Voandzeia subterranea) (BNM) in 10 experimental African catfish, Clarias gariepinus, diets. Feed formulation was designed using mixture model. The inclusion level of the three protein ingredients varied between 0% and 60%. Remaining 40% comprised of basal ingredients kept constant for all 10 feeds. African catfish of average initial weight 35.2 ± 0.9 g were fed with one of the treatment diets for 28 days. The protein:lipid ratios of the diets (range 1.5–3.4:1) were used in evaluating the feed utilization and growth of the fish. We found that catfish performances were mainly depending on ingredients and not the ratio itself. The protein:lipid ratios in the diets made of plant ingredients were high but SGR was low. Specific growth rate (SGR) increased with the increase of feed FM content, being ca. 5% day−1 with 60% FM diet but ca. 2% day−1 at both 60% BNM and 60% SBM diets. SGR was similar (3.5% day−1) with diets of 30% BNM or SBM inclusion with 30% FM. Feed conversion ratio increased from below 0.6 of the 60% FM diet up to 1.5 (60% SBM) and 1.7 (60% BNM). Protein efficiency ratio decreased linearly with increasing FM substitution, but protein productive value (PPV) was similar for catfish fed 60% FM diet and its 50% substitution with BNM or SBM. These results suggest that protein:lipid ratio cannot be used in assessing nutritional performance if the source of feed ingredient vary widely. However, these results suggest that BNM can partly substitute FM and completely replace SBM in the diets of African catfish. Full article
(This article belongs to the Special Issue Nutritional Requirements in New Fish Species Under Culture)
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