Promotion of substrate based microbial biofilm in ponds: a low cost technology to boost fish production

Microbial biofilms have been found to increase fish production in ponds by increasing heterotrophic production through periphyton proliferation on available substrates. In this paper, the role of substrate based microbial biofilm in the production of Cyprinus carpio and Labeo rohita grown in ponds is investigated, using an easily available and biodegradable agricultural waste product (sugarcane bagasse) as substrate.

Effect of microbial biofilm in the nursery phase of mrigal, Cirrhinus mrigala

The experiment was conducted for 35 days in nine cement tubs (1 x 1 x 1 m) having 15 cm sandy-loam soil base with three treatments in triplicate, viz., cow dung alone at the rate of 1 kg/tub (T sub(1)), cow dung at 1 kg/tub and feed at 10% body wt/d in two meals (T sub(2)), and cow dung at 1 kg and paddy straw at 200 g/tub (T sub(3)). Both manure and substrate were added on dry weight basis. All the tubs were stocked with 10 fry each mrigal (100,000/ha) of average weight of 0.09 g, seven days after the addition of manure and substrate. The total plate count of bacteria in water did not vary much between the treatments and the mean values were 5.13, 5.49 and 5.85 (CFU x 10 super(4)/ml) in T sub(1) T sub(2) and T sub(3) respectively. The number of phytoplankters and zooplankters in water differed significantly between the treatments. The average number of attached algae (no./cm³) and fish food organisms (no./cm³) recorded on the substrate were 145.28 and 70.67, respectively. The mean final weight of mrigal differed significantly (P < 0.05) between the treatments with T sub(3) registering the highest value of 6.93 g followed by T sub(2) (5.01 g) and T sub(1) (3.37 g). The specific growth rate and growth increment of fish also followed the same trend as that of weight recorded in the different treatments. Survival was higher in T sub(2) (83.33%), followed by T sub(3) (80.00%) and T sub(1) (76.67%). The study demonstrates that by the introduction of biodegradable substrates like paddy straw into the culture systems, significantly higher growth and survival can be obtained in the nursery rearing of mrigal.

Application of whey protein incorporation with Cinnamon oil as a preservative in Huse huso fillet under chilled storage condition

Biodegradable protein-based film was developed by incorporating cinnamon essential oil (CEO) into whey protein concentrate (WPC) at level of 0.8% and 1.5% v/v. Then physical and mechanical properties of the films were evaluated. Adding CEO to the WPC matrix decreased the water vapour permeability of the films and water solubility. Films containing CEO showed significant antibacterial activity both gram-positive and gram-negative strains and exhibited significant inhibitory effect on the studied fungi. In continue, the effect of whey coating and whey coating incorporated with 1.5% CEO on quality and shelf life of Huso huso fillet during refregrated (4±1°C) storage period were also investigated. The control and treated fish samples were analyzed for microbiological (total viable count, psychrophilic counts), chemical (PV, TBA, FFA, pH, TVB-N), and sensory characteristics in 4-day intervals up of microbial, chmical and sensoy analyses indicated lower levels of PV, TBA, FFA, pH, TVB-N in coasted sampels and specially, those with CEO while were kept in refrigerator. Based on results, whey protein edible coating contain 1.5% cinnamon essential oil could enhance preserving ability Huso huso during storage cold.