Biodiversity of commercially important finfish species caught by mid-water and bottom trawls from two different coasts of Arabian Sea: Threats and conservation strategies

This study was conducted to estimate the diversity and the occurrence of commercially important finfish species collected by twenty fish sampling site of Sindh and Baluchistan coasts of the Arabian Sea in Pakistan from January to December 2019. Additionally, physicochemical characteristics of seawater were analyzed from these selected sites and found to be within suitable ranges required for fish growth and survive. A total of 81287 fish individuals were collected and identified as 49 species belonging to 26 families in our study. The most diversified family was Sparidae (13 species) followed by Carangidae and Lutjanidae (4 species), Mullidae, Serranidae, Ariidae (3 species), and Sciaenidae (2 species). The remaining 20 families were represented by only one species. The values of Shannon diversity index calculated for the four selected habitats revealed that high fish diversity was reported at Sonmiani Coast (H'=1.81), while less at Ormara Coast (H'=0.23). Likewise, Evenness index (E) was high at Sonmiani Coast (E=0.50) and less fish diversity was reported at Ormara Coast (E=0.06). Reducing risks to threatened marine species in coastal habitats also requires conservation actions at multiple scales. Thus, it was concluded that our study could be valuable in providing the more information’s regarding to the diversity of finfish species and their occurrence along the Pakistan Coast. Further, to better understand the effects, regular monitoring and conservation measures should be taken to mitigate the influence of anthropogenic activities and protect finfish diversity from further decline

Biofortified Diets Containing Algae and Selenised Yeast: Effects on Growth Performance, Nutrient Utilization, and Tissue Composition of Gilthead Seabream (Sparus aurata)

Efforts have been made to find natural, highly nutritious alternatives to replace fish meal (FM) and fish oil (FO), which can simultaneously promote fish health and improve the nutritional quality of filets for human consumption. This study evaluated the impact of biofortified diets containing microalgae (as replacement for FM and FO), macroalgae (as natural source of iodine) and selenised yeast (organic source of selenium) on gilthead seabream growth, nutrient utilization, tissue composition and gene expression. A control diet (CTRL) with 15% FM and 5.5% FO was compared with three experimental diets (AD1, AD2, and AD3), where a microalgae blend (Chlorella sp., Tetraselmis sp., and DHA-rich Schizochytrium sp.) replaced 33% of FM. Diet AD1 contained 20% less FO. Diets were supplemented with Laminaria digitata (0.4% AD1 and AD2; 0.8% AD3) and selenised yeast (0.02% AD1 and AD2; 0.04% AD3). After feeding the experimental diets for 12 weeks, growth was similar in fish fed AD1, AD2, and CTRL, indicating that microalgae meal can partially replace both FM and FO in diets for seabream. But AD3 suppressed fish growth, suggesting that L. digitata and selenised yeast supplementation should be kept under 0.8 and 0.04%, respectively. Despite lower lipid intake and decreased PUFAs bioavailability in fish fed AD3, compared to CTRL, hepatic elovl5 was upregulated resulting in a significant increase of muscle EPA + DHA. Indeed, filets of fish fed AD2 and AD3 provided the highest EPA + DHA contents (0.7 g 100 g–1), that are well above the minimum recommended values for human consumption. Fish consuming the AD diets had a higher retention and gain of selenium, while iodine gain remained similar among diets. Upregulation of selenoproteins (gpx1, selk, and dio2) was observed in liver of fish fed AD1, but diets had limited impact on fish antioxidant status. Overall, results indicate that the tested microalgae are good sources of protein and lipids, with their LC-PUFAs being effectively accumulated in seabream muscle. Selenised yeast is a good fortification vehicle to increase selenium levels in fish, but efforts should be placed to find new strategies to fortify fish in iodine.

Fishmeal Dietary Replacement up to 50%: A Comparative Study of Two Insect Meals for Rainbow Trout (Oncorhynchus mykiss)

The demand of optimal protein for human consumption is growing. The Food and Agriculture Organization (FAO) has highlighted aquaculture as one of the most promising alternatives for this protein supply gap due to the high efficiency of fish growth. However, aquaculture has been facing its own sustainability problem, because its high demand for protein has been traditionally satisfied with the use of fishmeal (FM) as the main source. Some of the most promising and sustainable protein substitutes for FM come from insects. The present manuscript provides insight into an experiment carried out on rainbow trout (Oncorhynchus mykiss) with a 50% replacement of FM with different larvae insect meals: Hermetia illucens (HI), and Tenebrio molitor (TM). TM showed better results for growth, protein utilization and more active digestive function, supported by intestinal histological changes. Liver histology and intermediary metabolism did not show relevant changes between insect meals, while other parameters such as antioxidant enzyme activities and tissue damage indicators showed the potential of insect meals as functional ingredients.

Spatiotemporal variations in length-weight relationship, growth pattern and condition factor of Periophthalmus variabilis Eggert, 1935 in Vietnamese Mekong Delta

Length-weight relationship (LWR), growth pattern and condition factor (CF) play a vital role in fish resource evaluation and management but data on this is limited for Periophthalmus variabilis. This is an amphibious fish that lives in the mudflats of the mangrove forests in the Western Pacific regions, including the Vietnamese Mekong Delta (VMD). This paper contributes to the understanding of the LWR, growth pattern and CF of P. variabilis. Fish specimens were collected by hand at four sites in the VMD from April 2020 to March 2021. The analysis of 495 individual fish (259 females and 236 males) showed that fish weight could be estimated from a given fish length due to high determination values (r2 = 0.70 − 0.97). Dusky-gilled mudskippers of the VMD exhibited positive allometry, as indicated by their larger than 3 b value (b = 3.094 ± 0.045, p = 0.04). However, the growth pattern of the mudskipper between the sex and maturation stage (immature versus mature) showed isometry. These fish displayed positive allometry in the dry season (b = 3.138 ± 0.065) (>3, p = 0.04) but isometry in the wet season (b = 3.058 ± 0.061) (≈3, p = 0.34). Fish growth ranged from isometry to positive allometry and varied by site (b = 2.850 ± 0.103–3.370 ± 0.114) and month (b = 2.668 ± 0.184–3.588 ± 0.299) based on the b value. The CF of P. variabilis was not affected by sex (p = 0.29), body size (p = 0.64) or season (p = 0.43), but was affected by site (p = 0.01) and month (p = 0.01). The CF of this species (1.05 ± 0.02) was higher than 1 (p < 0.001), indicating that the fish adapted well to their habitat.

Effect of Supplementation of Dried Bioflocs Produced by Freeze-Drying and Oven-Drying Methods on Water Quality, Growth Performance and Proximate Composition of Red Hybrid Tilapia

Supplementation of dried bioflocs for red hybrid tilapia (Oreochromis sp.) was examined during 57 days of feeding trials. Five experimental treatments; T1 (the control; without bioflocs), T2 (4% freeze-dried bioflocs), T3 (16% freeze-dried bioflocs), T4 (4% oven-dried bioflocs), and T5 (16% oven-dried bioflocs) were prepared to examine the water quality, growth performance and body composition of red hybrid tilapia. T2 and T4 treatments resulted in a higher growth rate and survival similar to the control, while T3 and T5 treatments showed the lowest values of growth performance among all treatments. T1 treatment showed the best quality of culture water followed by T2 and T4 treatments, while T3 treatment resulted in poor water quality followed by T5 treatment. Based on these results, the ratios of bioflocs (4% and 16%) had more effect on fish growth and water quality than the drying methods (freeze-drying and oven-drying). The ratio of 4% freeze-dried or oven-dried bioflocs provided higher growth rates and better water quality parameters similar to the control, while the ratio of 16% showed the worst growth performance and water quality in the present study. In addition, body compositions of tilapia fed 4% dried bioflocs showed better nutritional value than tilapia fed 16% dried bioflocs. Protein and energy levels showed an increasing trend with decreasing supplement levels of bioflocs. Moisture content was significantly higher when supplementation of 16% bioflocs was used. Overall, supplementation of 4% freeze-dried or oven-dried bioflocs can be successively included in red hybrid tilapia diets without any effects on growth or body composition and can result in a good quality of culture water for red hybrid tilapia.

EFFECT OF ADDITION OF TEMULAWAK EXTRACT (Curcuma xanthorriza) ON ARTIFICIAL FEED ON GURAMI FISH GROWTH (Osphronemus goramy)

The problem with gouramy cultivation was slow growth due to the short intestines of gouramy so that the absorption of feed takes longer and less. Several previous studies used temulawak in the form of flour, extract, oil which was applied to carp, tilapia, milkfish, catfish. The addition of extract, temulawak flour to the feed gave an increase in growth both in length and weight in the test fish. The purpose of this study was to determine whether or not the effect of temulawak extract on the growth of gouramy fish. This research was conducted for 45 days. This research was conducted by experimental method using a completely randomized design (CRD) with 5 treatments (P) 3 times replication (U), in order to obtain 15 experimental units. Treatment 0 Control (without temulawak extract), Treatment 1 Provision of temulawak extract with a concentration of 14%/kg feed, Treatment P2 Administration of temulawak extract with a concentration of 16%/kg feed, treatment P3 Administration of temulawak extract with a concentration of 18%/kg feed, and treatment P4 administration of temulawak extract with a concentration of 20%/kg feed. The results showed that in the P0 treatment the absolute weight gain was 0.78 grams, in the P1 treatment the absolute weight was 0.58 grams, the P2 treatment was 0.33 grams, the P3 treatment was 0.37 grams, and in the P4 treatment it was obtained The result of absolute weight gain was 0.39 grams. The results showed the absolute length increase ranged from 0.35-0.57 cm. It can be concluded that the addition of temulawak extract to the commercial feed of carp has no significant effect on absolute weight, absolute length, survival rate and feed efficiency level.

EFFECT OF ADDITIONAL GINGER (Zingiber officinale var. amarum) ON FEED ON THE GROWTH AND SURVIVAL LEVEL OF GOLDFISH (Cyprinus Carpio)

Goldfish is one of the most popular freshwater cultivated fish because it is one of the freshwater commodities that has economic value and is sold at a price that is affordable to all groups. Ginger is a natural ingredient that can stimulate fish growth. The purpose of this study was to determine the effect of adding ginger to feed and to determine a good dose of ginger for growth and survival rates of carp (Cyprinus carpio). This research was conducted by experimental method using completely randomized design (CRD) with 5 treatments and 3 replications. The treatments given were Treatment 1: 0 grams, without adding ginger / kg of feed (control), Treatment 2: 2.5 grams of ginger / kg of feed, Treatment 3: 5 grams of ginger rhizome / kg of feed, Treatment 4: 7.5 grams of ginger / kg of feed, Treatment 5: 10 grams of ginger / kg of feed. The results showed that the addition of ginger had no significant effect on absolute length growth, absolute weight growth, feed conversion ratio, and feed efficiency, but had a significant effect on the survival rate of goldfish (cyprinus corpio). And a good dose of ginger is in P2 treatment with a dose of 2.5 grams of ginger, because it has been able to show a good survival rate of 100%.

GROWTH AND EXPRESSION PATTERN OF GROWTH-RELATED GENES IN THE FAST-GROWING GIANT GOURAMI Osphronemus goramy

Growth improvement of the giant gourami through molecular assisted selection offers a breakthrough solution regarding the slow growth problem in culturing the fish species. However, gene molecular expression studies and gene mapping information are scarce for this species. This study aimed to evaluate the growth, expression of the growth-related genes and compare the gene expressions between fast-growing (FG) and slow-growing (SG) fish. The polymorphism screenings were also conducted within the GH sequence of the FG and SG populations. Fish growth was analyzed by measuring length and weight once a month. The expression levels of GH, IGF1, AMPK, ARS-I, ALT, and AST genes were analyzed using real-time PCR. Twenty-five days old fish were reared for 30 days. The fish were continuously reared separately based on their body weight (BW) for 85 days until reaching 140 days old. At the end of the rearing period, the BW growth rate of the FG population was 1.569-fold higher, and body length (BL) growth was 1.056-fold higher than the SG population. FG fish have higher gene expression than the SG fish, indicating the important role of gene expression in fish growth. The polymorphisms screening within the GH sequences showed no significant difference between FG and SG fish of giant gourami. These research results provide valuable information in developing the marker-assisted selection for growth traits in giant gourami.