Three experiments were conducted to investigate the use of pollen from Pinus tabulaeformis (PP), as a possible replacement for synthetic 17-alpha-methyltestosterone (MT) in Nile tilapia, Oreochromis niloticus larvae diets. In experiment 1, the attractability of a diet containing PP (640mg/kg) compared to a control diet containing no PP was assessed. Experiment 2, lasting 8 weeks, evaluated the effects of PP on growth, food conversion efficiency, survival, and sex inversion compared with that of 17a-methyltestosterone (MT). Results showed that after 60 days of feeding, 100% of Nile tilapia fed the MT diet converted to male; this was statistically similar to the percentage of fish fed the PP diets (81.0% to 89.1% male, p<0.05). Results of the growth trial showed that final weight (FW) and weight gain (WG) of fish fed diets containing 0.08 g/kg PP and 0.64 g PP/kg were significantly higher than those fed the MT diet (p<0.05). Feed intake (FI) of all experimental fish were statistically similar (p>0.05). The group fed 0.08 g PP/kg diet exhibited significantly higher SGR than the MT group. The MT group exhibited lower food conversion efficiency (i.e. higher FCR) than the control group. Fish fed diets containing 0.08 and 0.64 g PP/kg exhibited better FCR than those fed the MT diet. Survival was statistically similar for all dietary treatments (p>0.05). In experiment 3, fish larvae were fed: no PP (control diet), a medium dose (0.32 g/kg), and a high dose (0.64 g/kg) of PP for 14 days and assayed for alpha amylase and trypsin activities. Results showed that diets containing PP were significantly more attractive to the fish than the control diet (p<0.05) for the first 5 min. At the 6th min, results were statistically similar for both PP diets. In conclusion, PP could replace MT in effecting sex reversal from female to male with statistically similar results; it could also promote better growth and food conversion efficiency at the minimum dietary level of 0.08 mg PP/kg.

Mangrove crab Scylla serrata is associated with mangroves throughout the Indian and Pacific oceans. This species is crucial to aquaculture and fishing. As wild stocks decline and demand rises, mangrove crab aquaculture has become increasingly popular. However, feed development research and its quality are still meager in the industry. This study examined the interactive effects of different levels of crab shellmeal (CSM) to fishmeal (FM) replacement on proximate composition, feed utilization, carcass composition, growth, and survival performance of mangrove crab S. serrata. Four formulated diets were prepared, and one for chopped trash fish (TF) supplement: 30% FM and 0% CSM (Diet 1) as a negative control, 20% FM and 10% CSM (Diet 2), 10% FM and 20% CSM (Diet 3), 0% FM and 30% CSM (Diet 4), and TF as a positive control (Diet 5). Experiments were conducted in each group for 30 days with ten replicates. Results revealed that formulated diets using different levels of CSM and FM did not significantly affect mangrove crabs' growth and survival rates as well as feed utilization. However, the proximate composition of Diet 4 was significantly higher among other experimental diets. Moreover, the crab's whole body composition (ash, moisture, carbohydrates, crude protein, crude fat, and calories) with different levels of CSM and FM was significantly improved. Hence, it is possible to enhance the carcass composition and proximate composition by supplementing CSM; however, it has no effect on feed utilization, as well as the growth and survival rates of mangrove crab S. serrata.

Three experiments were conducted to investigate the use of pollen from Pinus tabulaeformis (PP), as a possible replacement for synthetic 17-alphamethyltestosterone (MT) in Nile tilapia, Oreochromis niloticus larvae diets. In experiment 1, the attractability of a diet containing PP (640mg/kg) compared to a control diet containing no PP was assessed. Experiment 2, lasting 8 weeks, evaluated the effects of PP on growth, food conversion efficiency, survival, and sex inversion compared with that of 17a-methyltestosterone (MT). Results showed that after 60 days of feeding, 100% of Nile tilapia fed the MT diet converted to male; this was statistically similar to the percentage of fish fed the PP diets (81.0% to 89.1% male, p<0.05). Results of the growth trial showed that final weight (FW) and weight gain (WG) of fish fed diets containing 0.08 g/kg PP and 0.64 g PP/kg were significantly higher than those fed the MT diet (p<0.05). Feed intake (FI) of all experimental fish were statistically similar (p>0.05). The group fed 0.08 g PP/kg diet exhibited significantly higher SGR than the MT group. The MT group exhibited lower food conversion efficiency (i.e. higher FCR) than the control group. Fish fed diets containing 0.08 and 0.64 g PP/kg exhibited better FCR than those fed the MT diet. Survival was statistically similar for all dietary treatments (p>0.05). In experiment 3, fish larvae were fed: no PP (control diet), a medium dose (0.32 g/kg), and a high dose (0.64 g/kg) of PP for 14 days and assayed for alpha amylase and trypsin activities. Results showed that diets containing PP were significantly more attractive to the fish than the control diet (p<0.05) for the first 5 min. At the 6 th min, results were statistically similar for both PP diets. In conclusion, PP could replace MT in effecting sex reversal from female to male with statistically similar results; it could also promote better growth and food conversion efficiency at the minimum dietary level of 0.08 mg PP/kg. The IJA appears exclusively as a peer-reviewed on-line open-access journal at http://www.siamb.org.il. To read papers free of charge, please register online at registration form. Sale of IJA papers is strictly forbidden.

Groupers are among the most popular fish commodities worldwide owing to their palatability and appearance. However, their body pigmentation considerably affects their consumer acceptability and pricing, making their culture challenging. The present study aimed to improve the body pigmentation of the leopard coral grouper (Plectropomus leopardus) by investigating the effects of tank color, shading, and feed additives over 28 days. The fish were reared in tanks of different colors (white, black, red, and green), and their net cages were shaded at 0%, 50%, and 80%. The fish reared in the black and green tanks or under 80% shading exhibited the most vibrant skin coloration. Skin color enhancement was tested in feeding trials, during which the fish were fed different concentrations of additives: astaxanthin (0 (control), 1000, 2000, and 3000 mg), vitamin E (1000, 2000, and 3000 mg), and plant extracts (250, 500, and 750 mg) kg-1 of diet. Fish fed the 3,000 mg of astaxanthin kg-1 diet displayed the best pigment enhancement, whereas those fed with vitamin E and plant extracts showed reduced pigmentation. Feeding with different ratios (0%, 10%, 20%, and 30%) of krill meal in the diet showed that body pigmentation was best enhanced by 20–30% krill meal. In conclusion, our results imply that black- and green-colored rearing tanks under 80% shading and a diet with 20–30% krill meal and 3,000 mg astaxanthin kg-1 constitute ideal conditions to enhance the body pigmentation of P. leopardus.

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