The biogas plants of different sizes and capacities are spreading in India rapidly with the increasing energy demand. Farmers –including fish farmers- are among the target groups who have been benefitting from biogas units.
In regard to fish farming, and based on its nutritive merit, the use of biogas byproduct (biogas slurry) in aquaculture has proven a viable environmentally approach and hence has been promoted and adopted in Indian aquaculture especially in carp culture. There are reports showing that the application of biogas slurry at 15 to 30 tons/ ha/year has given fish yields which are about 60% higher as compared to the application of undigested cow dung.
There are different utilization scenarios for the biogas slurry whether discharged directly it into fish pond or incorporated in the feed mixture with other feed ingredients such as rice bran or oil cake to the extent of 50%.
Meagre (meager) proved to be a new candidate in Egyptian aquaculture. The preliminary efforts to adapt Meagre to aquaculture were done by the private sector, starting in 1996 in Damietta Governorate. Ongoing meagre farming operations rely on trash fish and small shrimp as the only feeding source whereas a harvest of about 12 tons/ha have been achieved over 285 days with 1.25 kg as an average weight/fish. In this situation and as expected, the feed conversion ratio is poor with an average of 9 (feed): 1 (gain).
Because there is a growing interest to incorporate meagre in Egyptian aquaculture, there is a new initiative that targets the artificial spawning and production of meagre seeds. Also, field trials have been conducted on private farms for evaluating the impact of artificial feed with 40 and 50% crude protein on the growth performance and production of the species. These initiatives are expected to support the development of meagre aquaculture in Egypt whether for local market and possibly for export.
The existing farming of meagre or (meager) in Egypt relies on wild caught fry and fingerlings. The collection is carried out by the Mediterranean coast and takes place from April till early June. The estimated number of collected meagre fry and fingerlings goes from 2 to 5 million/year. The preferred habitats for the species are located between 5 and 15 m depth, and characterized by the presence of shelters beneath rocky boulders next to sea-grass meadows. The size of collected fry or fingerlings ranges from about 2.5 com during April, 5-10 cm in May and exceeds 10 cm at the ending of the season in June.
The Chinese hatchery system became most popular throughout India especially the efficiency of the system is high and the cost (construction and operation) is less compared to other systems. These hatcheries are used for Chinese carps as well as Indian major carps.
The video shows a spawning tank and three incubation tanks. The spawning tank is with an inside diameter of 8 m and holds 50 cubic meters of water. The inside depth at the periphery is 1.20 m which slopes down to the center at 1.50 m. The design of the spawning tanks allows fertilized eggs along with water to be transferred into incubation tank for hatching. The water flows in the spawning pool create an artificial riverine condition for the fish to breed.
The three other tanks shown in the video are for the incubation and hatching of fertilized eggs. Tanks are circular with about 3.6 m internal diameter. Each of these tanks has two chambers (outer and inner). The inner chamber is encircled with a screen of the right mesh that allows only water to pass through. The tank is often with 9-12 m3 of water holding capacity. These tanks are equipped with outlets through which that hatchling pass through into the larval tanks (not shown in the video). Water speed and direction in these tanks assures favorable circulation of eggs and protect them against mechanical injury.
Usually boats are pulled off-shore. However, this interesting video shows an unusual task for a truck that is pushing fishing boats from the sea. The sun set in at the end of the video indicates the end of the daily fishing trip for fishermen. The quick and straight pushing of this boat -and must be for other boats lined in the video- tell the experience of the truck driver who was able to safely finish the task in about 30 seconds. Looking at the truck appearance especially in regard to the absence of the plate and the lack of left beam, it seems that boat pushing –regardless its legality- is the main –if not the only- daily duty of such truck.
The video shows prior-harvest sampling of Nile tilapia (Oreochromis niloticus). As seen in the seine, sampled tilapia falls in the category of super tilapia that averages or exceeds 400-500 g. Based on household patterns of fish consumption, the super tilapia is not affordable to low and/or medium-income families due to its higher price. This indicates a relative difficulty in marketing this premium-size tilapia and limits their target consumers to high income households. Moreover, the economics and so the profitability of super tilapia compared to grade-1 tilapia (200-250 g) has not been scientifically assessed. In other words, farm economics might be better and marketing would most likely be easier if the first grade tilapia is targeted instead of super-size especially when the economic law of diminishing return is considered. However, the super tilapia of 800 g and above could be justified if tilapia is processed and filleted for either local market or for export.
Source: E.B. Worthington, Middle East Science, 1946. Publisher: London: His Majesty’s Stationery Office
Caption of the photo: A new plant at Aqaba for sharp-freezing and cold-storing fish for Palestine.
The paragraph on fish freezing and cold-storing reads in the reference as follows: “The Gulf of Aqaba has recently received special attention as the site for a fishery because it gives access to the Red Sea for Palestine and Transjordan, both of which abut on to the Gulf’s northern tip. For Transjordan, indeed, this is the only possibility of a fishery of any kind, and Arab enterprise has attempted developments there for the past fifteen years or so, but without conspicuous success. Palestine, having a protein shortage during the war and insufficient fish available from other sources, launched a scheme at Aqaba in 1943, with the object of delivering lorry-loads of fish to its main centres of population at least once a week. The method has been to encourage the local Arab fishermen, in the Gulf itself and around the point of Sinai as far as Tor in the Gulf of Suez, to catch more and to sell their catch. The fish so acquired, mostly at the mouth of the Gulf of Aqaba, are taken by a ship of 150 tons, which is specially fitted with refrigerating apparatus, to the village of Aqaba. Here a large plant for quick-freezing and ice-making has been established to receive the fish and to store it at times when road transport is impossible. From Aqaba the fish is taken in refrigerated lorries by the Sinai route to cold stores at Lydda, from where it is redistributed to retailers in the towns”.
The photo shows the Mubone fish station, Bujumbura Province. The station has a total of 23 ponds and 100 hapas which are installed in one pond and used for the reproduction and nursing of Nile tilapia. The species farmed/searched on the station are Nile tilapia, Oreochromis niloticus and African catfish, Clariasgariepinus. The main hatchery brood stock of African catfish is kept on the station.
The duck and her ducklings shown in the second photo are farmed and reproduced on the same station, but in a small number.
The photo was just taken after the rehabilitation of Kavogero fish farming station, Kirundo province. One can see the color of unfertilized pond water. The station has nine earthen as well as two hen houses what are constructed above two of the fish ponds. Tilapia and African catfish, Clarias Gariepinus are the species farmed/searched in the station.
