Background The objective of the present study was to evaluate the growth performance and feed utilization of African catfish Clarias gariepinus fed a commercial diet and reared in the biofloc system enhanced with probiotic. Methods The treatment was the frequency of probiotic application into the cultured system, namely, 5-day interval, 10-day interval, and 15-day interval for 60 days of experiment. Biofloc culture was grown in an experiment tank (vol. 2000 L) by mixing the probiotic ( Bacillus sp.) 10 mL and molasses 200 mL per liter of water.  The fish was stocked into the biofloc system 7 days after cultured at stocking density of 1000 fish tank -1.  The fish was fed a commercial diet that contains 38% crude protein, twice a day at satiation. The application of probiotic was reperformed after 5 days, 10 days, and 15 days after stocking. Results The study showed that the growth performance, survival, and feed utilization of African catfish were higher in the treatment at 5-day intervals over 60 days. The ANOVA test showed that the application frequency of probiotic into biofloc system of cultured media had the significant effect on the growth performance, survival rate, and feed utilization of African catfish. Conclusion The best growth performance and feed utilization were  found at the application of probiotic into biofloc system at 5-day intervals over 60 days.

Background: High stocking density and intensive feeding in aquaculture systems lead to the accumulation of organic waste, which results in an increase in ammonia, nitrite, and nitrite concentrations in culture media. Biofloc is a potential technology to overcome this problem. The starter is a crucial carbon source for bacteria in the formation of biofloc. The objective of the present study aimed to explore the best starter of biofloc in a red tilapia Oreochromis niloticus culture system. Methods: A completely randomized design with four levels of treatment was used in this study. The tested starter was (A) control treatment, biofloc without starter, (B) biofloc with molasses starter, (C) biofloc with tapioca starter, and (D) biofloc with sucrose starter. The floc was cultured in 100-L tanks with a salinity of 17 ppt. The tanks were stocked with O. niloticus with a size of 3.71±0.11 cm at a stocking density of 30 fish per tank. The fish were fed on a commercial diet two times a day at satiation for 40 days. The ammonia, nitrite, and nitrite concentrations were measured for an interval of 8 days. Results: The study showed that the NH3-N range was 0.02–0.07 mg L−1 (mean, 0.03 ± 0.02 mg L−1), NO2-N range was 0.20–0.43 mg L−1 (mean, 0.25 ± 0.12 mg L−1), and NO3-N range was 0.90–3.20 mg L−1 (mean, 1.42 ± 1.19 mg L−1). Conclusion: Among the starters tested, molasses was found to be the best for biofloc in tilapia culture.

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Background: High stocking density and intensive feeding in aquaculture systems lead to the accumulation of organic waste, which results in an increase in ammonia, nitrite, and nitrite concentrations in culture media. Biofloc is a potential technology to overcome this problem. The starter is a crucial carbon source for bacteria in the formation of biofloc. The objective of the present study aimed to explore the best starter of biofloc in a red tilapia Oreochromis niloticus culture system. Methods: A completely randomized design with four levels of treatment was used in this study. The tested starter was (A) control treatment, biofloc without starter, (B) biofloc with molasses starter, (C) biofloc with tapioca starter, and (D) biofloc with sucrose starter. The floc was cultured in 100-L tanks with a salinity of 17 ppt. The tanks were stocked with O. niloticus with a size of 3.71±0.11 cm at a stocking density of 30 fish per tank. The fish were fed on a commercial diet two times a day at satiation for 40 days. The ammonia, nitrite, and nitrite concentrations were measured for an interval of 8 days. Results: The study showed that the NH3-N range was 0.02–0.07 mg L−1 (mean, 0.03 ± 0.02 mg L−1), NO2-N range was 0.20–0.43 mg L−1 (mean, 0.25 ± 0.12 mg L−1), and NO3-N range was 0.90–3.20 mg L−1 (mean, 1.42 ± 1.19 mg L−1). Conclusion: Among the starters tested, molasses was found to be the best for biofloc in tilapia culture.

Plastic waste pollution in the land and the river continues to rise. Plastic waste including marine pollution and debris can menyebab disrupt aquatic ecosystems. However, hazards of plastic waste pollution in the waters are still poorly understood by the public, especially for the people of Kampung Sungai Kayu Ara. To give knowledge to people in Kampung Sungai Kayu Ara Sungai Siak Apit about the dangers of plastic waste pollution in the rivers and sea required educational activities. So that more people know and understand the dangers of plastic waste, the public needs to be educated and understanding through extension activities. Extension activities carried out in Kampung Sungai Kayu Ara in September - October 2017. Implementation of education using lecture and discussion of the material presented. Conducted outreach activities to broaden the public about the negative impact of plastic waste so as to reduce the environmental impact of plastic waste on the river and the sea. The results show that the public targeted activity seen appreciation in receiving education of the activities carried out, the participants begin to recognize and understand the material presented and an increase understanding and knowledge about the dangers of plastic waste pollution between 65-80%.