The concept of waste-to-wealth means moving the waste from an exhausted utility platform to a valuable and desirable level. These transformations require some forms of energy and factors of production. As global production of fish is growing, a large quantity of food is available for processing and is, therefore, growing the amount of waste produced. Such by-products or waste in the form of non-edible tissues, such as bones, skin or scales, swim bladders, fins, intestines, blood, roes, liver, etc. are a rich source of valuable components such as protein, lipids, vitamins, and minerals.
If there is anything fish farming and aquaculture as a whole can teach farmers, it’s that nothing is a waste, you can reuse any material or product whatsoever, however, and most farmers don’t have enough knowledge as to those materials that can be reused or even how to properly use to the materials to avoid wastage in the first instance.
The aspect of fish processing alone generates more waste in fish farming. It is estimated that after filleting, fish processing waste accounts for around 75 percent of the total weight of the fish. Approximately 30% of the total weight of fish remains as waste in the form of skins and bones during the preparation of fish fillets. This waste is an excellent raw material for the preparation of products of high value like protein foods.
Recovery of marketable by-products from fish wastes is an effective waste management technique for the industry.
The three most common methods of aquatic waste use in aquaculture are fishmeal and oil production, silage production, and waste use in organic fertilizer production. In the course of the piece, these three methods will be explained, at least to give fish farmers some knowledge on how to go about with their “waste”.
FISH MEAL AND OIL
The conventional processing of fish meal typically requires the cooking of fish waste to remove the oil from the rest of the material and to ensure that all pathogenic and spoilage species are killed. Fish meal is a highly concentrated nutritious feed supplement made up of high-quality protein, minerals, B group vitamins such as cyanocobalamin (Bl2), choline,
It contains niacin, pantithenic acid, and riboflavin. Fish meal is reached in essential amino acids that cannot be synthesized by the animal body, making it an unrivaled constituent of feedstuffs.
There are also some unknown growth factors in a fish meal that give animals better growth. The biological value of fish meal protein is very high. Fish meal is used in animal feed, fish and shrimp feed as an ingredient.
Fish oil ‘is obtained from certain fish species or the waste materials from fish processing. The name of the fish oil varies depending on the raw material species. For instance, herring oil, sardine oil, etc. If after production the fish species is unknown it is called miscellaneous fish oil. Fish liver oils were used for therapeutic purposes in treating deficiencies in Vitamin A and D. Cod, haddock, and shark is the principal sources of liver oils. Halibut and tuna liver oils are also rich sources of vitamins A and D. In addition to its limited use in human nutrition, body oil is more important as an industrial product.
Fish oil is used in the manufacture of detergents, rubber, lubricants, printing inks, leather and cosmetics, stearic acid, glycerine, soap or candles, and pharmaceuticals. Fish body oil is used for human consumption and control of human ailments.
Fish silage is a liquefied fish protein and whole fish or fish pieces, preserved by adding an acid or by bacteria creating anaerobic lactic acid. The need to preserve fish by ensilaging, i.e. the process of making fish silage, arose when it became necessary to preserve large quantities of pelagic fish catches or waste for fish processing such as viscera, head fins, filleting waste. Unlike fish meal, fish silage requires little energy for production. Fish silage is used as fodder for cattle and fish/prawn. You can use either the whole mass or the liquid that has been decanted. The silage is mixed with rice bran or other feed ingredients if a solid feed is desired. The advantages of fish silage over fishmeal include no spoilage, almost sterile, cost-effective feasibility, low energy demand, and easy drying.
WASTE USE IN ORGANIC FERTILIZER PRODUCTION
Fish waste and bacteria provide nutrients for growing plants within a recirculating network. The fish water is carefully filtered and comes into contact with the roots only to eliminate the potential for pollution. Then plants take those nutrients up and return clean water to the fish. When composting such waste as fish parts, fish waste is mixed with plant waste like wood chips, leaves, bark, branches, peat, or even sawdust. As microorganisms break the fish down, they generate lots of heat, which serves to pasteurize the resulting fish compost, in turn eliminating any odor and killing disease organisms and weed seeds. After several months, the resultant product is rich humus lauded as a nutrient-wealthy fertilizer for soil amendment.
Other products made from fish waste/ byproducts include;
Fish glue may be made from the skin and head of the fish. If necessary, the skin of fish may be preserved by salting, if for a short time, or by drying for longer periods, before glue-processing. Fish glue is used for wood, paper, and leather fastenings. It is also used for labeling and bookbinding.
Calcium powder extracted from the backbone of the tuna may be used in the diet to counter calcium deficiency, particularly among children. Calcium deficiency can lead to bone failure and spine curvature in children. Calcium is known to be essential for many functions in our bodies including teeth and bone strengthening.
Pearl essence is a suspension of crystalline guanine in water or an organic solvent, Guanine is an iridescent material found in the epidermal layers and scales of most pelagic species of fish like oil sardine, mackerel, herring, etc. The pearl essence is used in the manufacture of artificial pearls for the most important use of the pearl essence and is used on such diverse items as shoe, pencil, fishing rod, spectacle frame, walking stick, ashtray, vanity bag, book cover, and even textile finishes.
The use of waste-products is an important cleaner production tool for the industry, as it can potentially produce additional revenue and the cost of disposal for these materials.