Utilization of the fish waste self-brine of fish curing industry as farm fertilizer

Large quantities of self-brine accumulating in curing tanks during the process of commercial fish salting is mostly wasted at present. This liquor exuded from the fish during the process of salting contains considerable amounts of soluble proteins and minerals. Due to the presence of organic matter the self-brine quickly putrefies causing nauseating smell. This renders the whole surroundings insanitary and often leads to health hazards to neighboring localities. Any economic method of utilising this waste brine and converting it into some useful product will be a tangible help to the fish curing industry. Hence, a method is given for converting this waste self-brine into a cheap and efficient fertilizer.

Studies on the probable sources of fungal infection and the control measures in a fish seed farm

The causes of mortality of fry of cultivable fishes in a fish seed farm were investigated. The mortality was due to fungal infection and the pathogen was Saprolegnia sp. The sources of infection were unhygienic breeding hapas, spawnery hapas in the cemented ponds, hatching jars and excess feeding. Application of one kg slaked lime followed by 75g of CuSo sub(4)(l-0.5 p.p.m.) and 150g of KMno sub(4)(2-1 p.p.m.) per each nursery (158m³ water) controlled the pathogen.

Integrated cage-cum-pond culture systems with high valued climbing perch (Anabas testudineus) in cages and low-valued carps in open ponds

An on-farm trial was conducted over 150 days to determine appropriate stocking ratio, growth and production of climbing perch (Anabas testudineus) in cages and carps in open water of ponds in eighteen farmers' ponds from Haluaghat Upazila at Mymensingh district of Bangladesh. One or two 1 m super(3) cage was suspended in each of 12 earthen ponds and other 6 ponds served as control without cages. Climbing perch of 2-3 g in size were stocked in cages while fingerlings of silver carp (Hypophthalmicthys molitrix), catla (Catla catla), rohu (Labeo rohita), mirgal (Cirhinus cirrhosus), rajputi (Puntius sarana) and common carp (Cyprinus carpio) were stocked at 1 fish/m super(2) with a species ratio of 5:4:4:4:2:1 in open water of all ponds to give cage to open-pond fish ratios of 1:1 (T sub(1:1)) and 2:1 (T sub(2:1)) and 0:1 (T sub(0:1)) as three treatments with six replicates each. Survival of climbing perch was higher in T sub(1:1) (61.67%) than that of T sub(2:1) (29.5%) and was significantly different (p>0.05) between the treatments. Stocking of small size climbing perch fry increased the mortality rate in cages. The net yields of Thai koi were 0.13±0.01 (t/ha) and 0.10±0.01 (t/ha) in treatments T sub(1:1) and T sub(2:1), respectively and both were significantly different (p>0.05). Survival of-open-pond carps was high, ranging from 50 to 91.67% with significantly lower in T sub(0:1) than that of T sub(1:1) and T sub(2:1) treatment. Net and gross yield of each carp species were significantly higher in the T sub(1:1) and T sub(2:1) treatment than that in T sub(0:1) treatment. Net revenues were positive but low in all treatments. Therefore, bigger size climbing perch with lower stocking ratio (T sub(1:1)) is suitable for integrated cage-pond culture of climbing perch and carps. However, more on-farm trials in different ecosystem with scientific interventions are necessary to develop the technology for further dissemination among the rural farmers.

Offshore fish farming

The article discusses offshore fish farming, which is commonly practiced in some countries in Asia, North and South America, and Europe. Environmental factors such as the exposure of the cage to wind and waves, and its management are also discussed.

Utilization of waste waters in fish production: preliminary results from fish culture studies in floating cages in a sewage pond, New Bussa, Nigeria

The utilization of waste waters in aquaculture were briefly reviewed. At the National Institute for Freshwater Fisheries Research (NIFFR), stocking density (20 to 160 fish/m super(3)) experiments using Sarotherodon galilaeus (without supplementary feeding) in floating cages were carried out in a sewage pond (0.4ha surface area). Cage culture of S. galilaeus was observed to have potentials in waste waters aquaculture. Recommendations were made on the execution of an intergrated waste water management and utilization.

Preliminary studies on bamboo floating cage and net enclosure culture in Kainji Lake basin

The main objective of this paper is to introduce bamboo floating cage and net enclosure fish culture technology aimed at producing fish from almost all available inland bodies of water in Nigeria. The experimental approach embarked upon at Kainji Lake Research Institute is discussed. Results obtained from these experiments would help in identifying the inherent problems of this culture system and in determining the urgently needed information that will serve as management and production guidelines for adapting the technology to local conditions of varying ecological characteristics in Nigeria. Ultimately, the project is aimed at increasing the productivity of fishermen/fish farmers and hastening the development of rural communities

Investment prospects of fish farming in the Jos-Plateau, Nigeria

The investment prospects of fish farming in the Jos-Plateau, Nigeria, strategically located in about the centre of the country are discussed with special reference to its numerous abandoned mine lakes and the tripartite role of government, universities and individuals. In the Jos-Plateau, about 17.0 km super(2) is covered by these disused mine lakes, making up about 20-30% of the area covered. In such enterprise, problems commonly encountered, like population growth and government planning policies, fish demand and supply, manpower, feed and seed availability, preservation, processing and marketing are discussed. Inspite of these, prospects still abound with regards to land-use of these numerous disused mine lakes and feed availability based on the principles of using both industrial and farm by-products for fish culture, processing and marketing. These potentials, if properly harnessed, will help to supplement the protein insufficiency in the diet of the populace. In this regard, proposals on the economics of production and sales, strategies for achieving these development goals, cost-benefit analysis and their implications in further development of fish culture are discussed

Indication of pollution in a teaching and research farm reservoir

The production and productivity of a water body is largely dependent on its quality. One major source of water pollution is from the agrochemicals from nearby farmlands. The quality of water in the Obafemi Awolowo University Teaching and Research Farm Reservoir (Ile-Ife, Nigeria) was monitored between October, 1993 and March, 1994. Structured questionnaires were administered to obtain information on the types of agrochemicals in use on the farm. Water samples were collected fortnightly for analyses of the physico-chemical parameters and ionic content of the water. Investigation revealed that 21 agrochemicals had been in use on the farm. The physico-chemical parameters of the water showed that the water was very poor in nutrient. The high concentration of ammonium ion contents of the water shows an indication that the residues of certain agrochemicals got into the water to pollute it. Agrochemicals should be used with great caution on farmlands especially in areas close to water bodies from which man obtains fish and other proteinous foods. This paper also suggests a regular monitoring of water quality of reservoirs in order to pick the earliest signs of pollution

Some ecological roles of Hippopotamus (Hippopotamus amphibious Linn. 1758) in fish production: possibilities for integrated fish-cum Agric production system

The common hippopotamus (Hippopotamus amphibious Linn. 1758) contributes to the productivity of aquatic systems where it lives. This paper reviews ecological roles of the hippo in this regard. Desk review of available literature information complemented with field observations were employed in the data collection. The ecological roles of the common hippopotamus being presented draw examples from East, West, Central and South African sub regions. The nutritional importance of the amphibious hippopotamus to rural communities was highlighted. In Southern Ethiopia, the Bodi, Bacha and Mura tribes eat hippo meat and this has led to severe hunting consequences on the wild populations of the animal. The important relationships between the hippopotamus and fish were presented. Hippopotamuses usually defecate in water and their excrements enrich the nutrients in the water resulting in favourable conditions for large fish populations. Some fish, including Labeo spp. were observed to feed on the micro-organisms and algae that grow on the skin of the hippotamus. A strong case was made for hippo-cum-fish integrated farm development in Nigeria based on ecological relationships so observed between the amphibious mammals and fish. This is one of the meeting points of fisheries and wildlife management that should be exploited for the benefits of the teeming Nigerian population

The relationship between some physicochemical parameters and plankton composition on fish production in ponds

The effect of physico-chemical parameters and plankton composition on fish production in ponds was investigated in six fish farms for eight weeks. The physicochemical parameters investigated were temperature=25-30 plus or minus C, transparency=0.45-0.57m, dissolved oxygen=3.0-10.9mg/l, pH=6.0-7.7, dissolved carbon dioxide=5.46-28.3mg/l, total alkalinity=44.37-80.0ppm, chemical oxygen demand=31.88-72.18mg/l and biological oxygen demand=0.66-48.34mg/l. Plankton composition varies and was made of four families of phytoplankton namely; Cyanophyceae, Chlorophyceae, Dinophyceae and Diatomida; and four families of zooplankton viz; Protozoa, Rotifera, Copepoda and Dinoflagellates. Farm 1 and 6 recorded the highest average weight of about 1.0kg and average total length of about 40.0cm for the two fish species. This study showed that fish yield was dependable on the quality and management of pond water characteristics

The relationship between some physicochemical parameters and plankton composition on fish production in ponds

The effect of physico-chemical parameters and plankton composition on fish production in ponds was investigated in six fish farms for eight weeks. The physicochemical parameters investigated were temperature=25-30 plus or minus C, transparency=0.45-0.57m, dissolved oxygen=3.0-10.9mg/l, pH=6.0-7.7, dissolved carbon dioxide=5.46-28.3mg/l, total alkalinity=44.37-80.0ppm, chemical oxygen demand=31.88-72.18mg/l and biological oxygen demand=0.66-48.34mg/l. Plankton composition varies and was made of four families of phytoplankton namely: Cyanophyceae, Chlorophyceae, Dinophyceae and Diatomida; and four families of zooplankton viz: Protozoa, Rotifera, Copepoda and Dinoflagellates. Farm 1 and 6 recorded the highest average weight of about 1.0kg and average total length of about 40.0cm for the two fish species. This study showed that fish yield was dependable on the quality and management of pond water characteristics

The production of freshwater fish for food

It has been estimated that in England and Wales fresh water covers some 340 square miles of which about one quarter is inhabited mainly by salmon and trout; in Scotland the lakes cover an area of 340 square miles. The principal object of this publication is to make available in handy form some of the methods, especially those involving the use of manures, by which crops of fish from water can be increased. The cultivation of water which this implies may be compared directly to the cultivation of farm land: the conditions for growth are made as favourable as possible, the seed is sown in the form of young fish, and after one or perhaps two growing seasons the crop is harvested. There are however many waters about the country where marketable fish are already available and can be removed without prejudice to, and indeed to the advantage of, sporting fisheries. In such cases it is necessary only to remove the fish and to rely on the natural processes of reproduction of those which are left to repopulate the water. Farming waters in the true sense is the concern of the greater part of this publication; the removal of crops of otherwise unwanted fish is considered in the last two sections on perch trapping and eel fisheries.

Environmental friendly aquaculture key to sustainable fish farming development in Nigeria

Aquaculture production in Nigeria has increased tremendously in recent times; along with this increase is the rise in the level of waste outputs from aquaculture practices. The discharge of waste from aquaculture operations on continuous basis leads to eutrophication and destruction of natural ecosystem in receiving water body. Controlled wastes production strategies is necessary to maintain sustainable aquaculture growth into the future, as long-term sustainability of fish culture systems depends on their ability to reduce their waste outputs. The release of solid wastes is mainly a function of the digestibility of various dietary components while the release of dissolved wastes is mainly a function of the metabolism of nutrients by the fish. This paper critically reviews the impacts of aquaculture wastes on the environment and the strategies to mitigate the effect of these impacts. Future trends and research needs on aquaculture induced effluents are outlined. As the amount of nutrient discharge is typically site and operation specific, effective farm management has been identified as the most important factor to avoid effluent pollution.

Essais d'utilisation de "nourrisseur à la demande" pour l'alimentation de Chrysichthys nigrodigitatus en cage-enclos

An experiment using demand feeder was carried out on the catfish Chrysichthys nigrodigitatus reared in cage-enclosure in the lagoon Ebrié (Côte d'Ivoire). The study lasted 5 months, from October to March, and showed that the demand feeder improves the growth rate of the fish and the feed conversion. It was able, as well as the conventional hand feeding, to show monthly variations of performances.

A preliminary assessment of water quality in fish cages on Lake Kariba, Zimbabwe

The water quality in fish cages on Lake Kariba was studied. The Kruskal-Wallis test was used to determine whether the water quality parameters differed significantly among the cage-types (cage-type effect). Secchi disc readings ranged from 2 to 4 metres, while temperature ranged from 23 degree C to 29.5 degree C. The observed conductivity was between 98.7 mu S/cm and 102.3 mu S/cm. The pH was between 6.31 and 7.82. Concentrations of dissolved oxygen varied from 1.55 to 6.47 mg/l, while dissolved oxygen saturation ranged from 22.3% to 83.1%. Within the same month, temperature did not differ significantly among cages. Conductivity, pH, dissolved oxygen concentration and dissolved oxygen saturation differed significantly among the 3 cage-types. Temperature and pH levels in the cages were close to the optimum levels for the culture of cichlids. Sub-optimal levels of dissolved oxygen occurred occasionally in the octagonal cages.