Introduction: Minerals, which comprise the ash of biological materials remaining after the organic substances have been completely burnt or oxidised in the body of all animals including fish, are known to be essential for cellular metabolism. Minerals, which are present in fairly large quantities in biological materials, are those of calcium, phosphorus, potassium, sodium, magnesium etc. The principal minerals present in micro quantities (or trace levels) are iron, manganese, zinc, copper, cobalt, selenium, chromium and iodine. Fish can get these minerals both from diet as well as from ambient water. The minerals are responsible for skeletal formation, maintenance of colloidal sys tems, regulation of acid-base equilibrium and for formation of some physiologically important compounds like hormones and enzymes. Mineral deficiencies can cause biochemical, structural aberrations and functional pathologies, which depend on several factors, including the duration and degree of mineral deprivation. Information on nutritional requirements of fish for trace elements is scarce particularly because many are needed in extremely small amounts and these pose difficult analytical problems too. If excess amount of the elements are ingested and assimilated, toxicity develops. In this communication importance of minerals which play signifi cant role in aquaculture nutrition has been highlighted. What is Minerals? On the basis of earth science (geology): The Glossary of Geology (Bates and Jackson, 1980, p. 401) defines a mineral as "a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties." Minerals differ from rocks, which are naturally occurring solids composed of one or more minerals. Rocks do not have a distinctive chemical composition or crystal structure. The earth science definition, however, is not always used define minerals. On the basis of U.S. government: The federal government defines minerals in its section on national mining and minerals policy (U.S. Code: Title 30, Section 21a) as including "all minerals and mineral fuels including some non-solid substances such as petroleum and natural gas." This definition is problematic, because it uses the word "minerals" in the definition. It also includes petroleum and natural gas, which are not considered minerals according to the earth science definition. As in the legal definition, water could be considered a mineral in some areas, depending on the statute and legal issue being considered. The U.S. Geological Survey publishes an annual Minerals Yearbook, which contains mineral commodities summaries. Mineral commodities are minerals according to the earth science definition, but also manufactured products such as abrasives, cement, and lime. Still confused? On the basis of Economy: When economists, engineers, and scientists use mineral in an economic context, they generally use the terms industrial minerals or mineral resources. The term mineral resources refers to the occurrence of any mineral commodity (as defined above) that could be removed from the ground. There are three categories of mineral resources: fuels minerals, metallic minerals (also called ore minerals), and industrial or construction minerals. The term fuels minerals refers to natural gas and petroleum, and thus minerals as defined by the federal government, but not minerals according to the earth science definition. The term metallic minerals (for example, iron ore, copper) almost always also refers to minerals according to the earth science definition. The term industrial minerals may include minerals according to the earth science definition, but more often refers to rocks (for example, limestone) and sediments (for example, sand and clays) according to the earth science On the basis of biological/ medical Science: The biological and health definition of minerals is in the context of "vitamins and minerals." Medical professionals use mineral to describe naturally occurring nutrients, which are inorganic elements and compounds such as iron, potassium, and calcium; rocks or fossil fuels are not included, although the minerals used in vitamins may be derived from rocks and fossil fuels. The health definition is still slightly different from the earth science definition, because it can include free elements such as calcium. In geology (and other sciences), calcium is considered an element that can be combined into a naturally occurring solid with a distinct crystal structure, such as calcite, which would be considered a mineral using the earth science definition. Generally minerals are 2 types. 1) Macro elements. 2) Micro elements (Trace elements). 1) MACRO ELEMENTS: Calcium (Ca): Source: Fish, milk, eggs, beans, nuts, figs, cabbage, cauliflower, asparagus Functions: •Formation of bone and teeth. •Regulates muscle contraction, including the heartbeat. •It also plays a key role in normal blood coagulation (clotting). •Calcium also plays a role in the release of hormones and enzymes. •Adequate calcium early in life may protect against obesity later. •Vitamin D helps our bodies absorb and retain calcium in the bones. Absorption: Calcium is readily absorbed through the gastro-intestinal tract (through vitamin D3 action), gills, skin and fins of fish and crustacea. In general, dietary calcium absorption is facilitated by dietary lactose (by forming a soluble sugar-calcium complex) and by high gastric acidities (by aiding solubilization of the calcium salt). Daily Amount Needed: Adults :1000-1200 mg/day. Children: 800 to 1300 mg/day Whole sardines: anchovy 580 mg of Ca/100g Phosphorus: Source: Fish meat, poultry, eggs, milk ready‐to‐eat cereal, dried peas and beans; bran and whole grains; raisins,prunes,dates Function: • Bone and teeth formation and maintenance, acid–base balance • energy metabolism, cell membrane structure • regulation of hormone and coenzyme activity. Absorption: Phosphorus must first be hydrolyzed within the gastro-intestinal tract by the enzyme phytase to inositol and phosphoric acid before it can be utilized and absorbed by the animal. As with calcium, the absorption of inorganic phosphorus salts is facilitated by high gastric acidity; the more soluble the salt the higher the availability and absorption of phosphorus. Daily Amount Needed: Adults need 700 mg/day. Children need: 800 to 1300 mg/day Sodium(Na) Source:Milk, meat, poultry, vegetables, bottled water Fish: 60 mg/100g Shellfish: 120-400 mg/100 g Fish breaded products: 300- 800 mg Functions: • Fluid and electrolyte balance, • Acid–base balance, • Regulates cell membrane permeability and • Nerve impulse transmission Functions Absorption: Absorbed from the gastrointestinal tract, skin, fins and gills of fish and crustacea. Daily Amount Needed: 19–50 yr: 1.5 g 50–70 yr: 1.3 g Potassium (K): Source: Canned tomato products, sweet potatoes, soynuts, clams, molasses, yogurt, tomato juice, orange, apple, bananas, peanuts, artichokes, fish, beef, lamb, avocados, Fish: 200-400 mg/100g Shellfish: 500-1000 mg/100 g Funvtions: • Fluid and electrolyte balance. • Acid–base balance. • Nerve impulse transmission. • Catalyst for many metabolic reactions, involved in skeletal Cardiac muscle activity Functions. Absorption: Absorbed from the gastrointestinal tract, skin, fins and gills of fish and crustacea. Daily Amount Needed: 19–50 yr: 1.5 g 50–70 yr: 1.3 g Magnesium (Mg): Source: Halibut, tuna, Spinach, beet greens, okra, Brazil nuts, almonds, cashews,bran cereal, dried peas and beans, chocolate, cocoa Fish: 21-45 mg/100 Shellfish: >50 mg/100 Functions: • Bone formation • Nerve transmission • protein synthesis • carbohydrate metabolism • enzyme activity Absorption: Magnesium is readily absorbed through the gastro-intestinal tract, gills, skin and fins of fish and crustacea. As with calcium and phosphorus, a proportion of the magnesium contained in plant foodstuffs may be present in the form of phytin (Ca or Mg salt of phytic acid). Daily Amount Needed: Adult: 400‐500 mg Children: 200‐300 mg Sulfur (S): Source: All protein foods- meat, poultry, fish, eggs, milk, dried peas and beans, nuts Functions: • Sulfur does not function independently as a nutrient, but it is a component of biotin, thiamin, and the amino acids methionine and cysteine. • The proteins in skin, hair, and nails are made more rigid by the presence of sulfur. Daily Amount Needed: Usually not required; sulfur deficiency is likely only when protein deficiency is severe. Absorption: Readily absorbed from the gastrointestinal tract of fish and shrimp 2) MICRO ELEMENTS (TRACE ELEMENTS) Iron (Fe): Source: Beef liver, red meats, fish, poultry, clams, tofu, oysters,lentils, dried peas and beans, fortified cereals, bread, dried fruit Iron in fish and shellfish Functions: • Plays an essential role in the transport, storage, and utilization of oxygen • Oxygen transport via hemoglobin and myoglobin; • Constituent of enzyme systems Irons in Present Fish and Shellfish: •Iron usually present in muscles in the range of 2 to 10 mg/kg of edible muscle •Dark muscle contains more iron than white muscle •The iron content of processed fish and fishery products may be influenced by the contamination from ferrous metals during cooking and processing •Direct contact of fillet with a deboning machine or any other metal appears to increase the iron content of minced fillet. Absorption: Iron is readily absorbed through the gastro-intestinal tract, gills, fins and skin of fish and crustacea. Dietary iron availability and absorption is usually depressed by high dietary intakes of phosphate, calcium, phytates, copper and zinc. In general, inorganic sources of iron are more readily absorbed than organic sources; theFe++) being more available for absorption than ferric iron (Fe+++). Reducing substances such as vitamin C enhance the absorption of non-haem iron. Daily Amount Needed: Men: 8 mg Women: 18 mg Children: 45 mg Zinc (Zn) Sources:Oysters, red meat, poultry, dried peas and beans, fortified breakfast cereals, yogurt, cashews, pecans, milk. Functions: • Tissue growth and wound healing • sexual maturation and reproduction • Nucleic acid metabolism • Immune function • Vitamin A transport, • Taste perception Zinc in fish and shellfish: •Among all food sources of animal origin, oyster is the richest source of zinc over 4000 mg/kg of dry tissue weight. •Several species of algae contain more than 1000 mg Zn/kg of dry weight. •Lobster meat contains a relatively lower amount of zinc than crab and other shellfish. Absorption: Zinc is readily absorbed from the gastro-intestinal tract, gills, fins and skin of fish and crustacea. Dietary zinc availability and absorption is reduced in the presence of phytates, and high dietary intakes of calcium, phopshorus and copper. Daily Amount Needed: Men: 11 mg Women: 8 mg Children: 40 mg Iodine (I) Source: Seafood, Iodized salt,, bread,dairy products Iodine in fish and shellfish. Functions: Component of thyroid hormones that regulate growth, development, and metabolic rate Iodines in Fish & Shellfish: • Iodine is the heaviest essential element in living organisms. • A dietary deficiency of iodine causes an enlargement of thyroid gland resulting in goiter •It is present in relative abundanc e in marine plants, fish and shellfish • Inhabitants of the coastal regions of Hokkaido Island in Japan consume large amounts of seaweeds, which may amount to 50 to 80 mg of iodine intake per day •The edible flesh of marine fish and shellfish may contain 0.3 to 3 mg iodine/kg •Iodine content in freshwater fish is generally lower than that of marine fish Daily Amount Needed: Recommended Dietary Allowance (RDA) Adult: 150 mcg (microgram) Children: 220 mcg (microgram) Selenium (Se): Source: Brazil nuts, tuna, beef, cod, turkey, egg, cottage cheese, rice, enriched and whole wheat bread. Functions: •Component of antioxidant enzymes •Immune system functioning •Thyroid gland activity Deficiency: Enlarged heart, poor heart function, impaired thyroid activity Selenium in fish and shellfish: •Selenium is recognized both as an essential trace element and a highly toxic agent •Excess selenium promotes dental caries. •Selenium reduces the toxicity of methyl. mercury, thus selenium deficiency accentuates heavy metal toxicity. •Fish contains substantially higher levels of selenium than red meats and poultry Daily Amount Needed Men and women: 55 mcg/day Children: 400 mcg/day Copper (Cu): Source: meats, seafood, nuts,seeds, whole grains, cocoa products, drinking water. Deficiency: Rare; anemia, bone abnormalities. Functions: • Used in energy metabolism • Used in the production of hemoglobin • Component of several enzymes • Used in energy metabolism •Copper is an essential component of numerous oxidation-reduction enzyme systems. For example, copper is a component of the enzymes cytochrome oxidase, uricase, tyrosinase, superoxide dismutase, amine oxidase, lysyl oxidase, and caeruloplasmin. •As a component of the enzyme caeruloplasmin (ferroxidase), copper is intimately involved with iron metabolism, and therefore haemoglobin synthesis and red blood cell production and maintenance. •Copper is also believed to be necessary for the formation of the pigment melanin and consequently skin pigmentation, for the formation of bone and connective tissue, and for maintaining the integrity of the myelin sheath of nerve fibres. Absorption: Copper is readily absorbed from the gastro-intestinal tract, gills, fins and skin of fish and crustacea. Dietary copper availability and absorption is reduced in the presence of phytates, and high dietary intakes of zinc, iron, molybdenum, cadmium, inorganic sulphates and calcium carbonate. Daily Amount Needed: Adult: 900 mcg Children: 10,000 mcg Manganese (Mn) Source:Whole grains, oat, bran, tea, pineapple, spinach,dried peas and beans. Functions: •Component of enzymes •Involved in the metabolism of carbohydrates, protein, and fat. •bone formation. Manganese in fish and shellfish •Manganese functions either as a cofactor activating a large number of enzymes to form metal enzyme complexes or as an integral part of certain metalloenzymes •Manganese is widely distributed in fish and other animal tissues. The highest concentrations are found in bone •However, significant amounts are also present in liver, muscle, kidney, gonad and skin •Mollusks and crustaceans contain significantly higher levels of manganese than fish usually in the range of 0.9 to 17.6 mg/kg •Most fish contain 0.1 to 0.4 mg Mn/kg. Absorption: Manganese is readily absorbed from the gastro-intestinal tract, gills, fins and skin of fish and crustacea. Dietary manganese availability and absorption is reduced in the presence of phytates, and high dietary intakes of calcium. Daily Amount Needed Men: 2.3 mg Women: 1.8 mg Adult UL: 11 mg Fluorine (F) Source: Fluoridated water, water that naturally contains fluoride, tea, seafood. Functions: •Formation and maintenance of tooth enamel •Promotes resistance to dental decay •Role in bone formation and integrity. Deficiency: Susceptibility to dental decay; may increase risk of osteoporosis Daily Amount Needed: Men: 4 mg Women: 3 mg Adult UL: 10 mg Chromium (Cr): Source: Broccoli, grape juice, whole grains, red wine. Functions: Cofactor for insulin Deficiency Insulin resistance, impaired glucose tolerance Daily Amount Needed Men:35 g Women:30 g Children: undetermined Molybdenum (Mo) Sources: Milk, legumes, bread Functions: •Component of many enzymes. •works with riboflavin to incorporate iron into hemoglobin. Deficiency: Unknown Daily Amount Needed Adult: 45 mcg Adult UL: 2000 mcg Cobalt (Co): •Cobalt is needed in very small amounts in the diet. It is an integral part of vitamin B12, cobalamin, which supports red blood cell production and the formation of myelin nerve coverings •Cobalt is available mainly as part of B12. •Meat, liver, kidney, clams, oysters, and milk all contain some cobalt •Ocean fish and sea vegetables have cobalt, but land vegetables have very little; •Cobalt, as part of B12, is used to prevent pernicious anemia; Toxicity can occur from excess inorganic cobalt found as a food contaminant. •Deficiency of cobalt is not really a concern if we get enough vitamin B12. Main Functions of Minerals in the Human Body: Minerals are essential nutrients found in many different types of plant- and animal-based foods. Macro-minerals, or those you require in greater amounts, include calcium, potassium, sodium, phosphorus, magnesium, chloride, and sulfur. Trace minerals, or those you need in smaller amounts, include iron, zinc, selenium, manganese, copper, iodine, cobalt, and fluoride. Both types of minerals support a wide variety of bodily functions, ranging from building and maintaining healthy bones and teeth to keeping your muscles, heart and brain working properly. Bone and Tooth Health: Your skeleton provides motility, protection and support for the body. It also stores minerals and other nutrients. Though they appear hard and unyielding, your bones are actually constantly being reabsorbed and reformed by your body. Several minerals make up the lattice architecture of your bones. Calcium is the most abundant mineral in your body and is found in your bones and blood. Along with the minerals phosphorus and magnesium, calcium gives your bones strength and density. This mineral also builds and maintains strong, healthy teeth. Calcium deficiency due to poor nutrition or illness can lead to osteoporosis, a condition in which the bones become brittle and less dense, increasing the risk of fractures. KidsHealth notes that foods that are rich in calcium include milk and other dairy products, green, leafy vegetables and canned fish with bones. Energy Production: You require oxygen to produce energy that is necessary for every bodily function and process. Red blood cells -- or erythrocytes -- carry oxygen to each of your infinite cells, where it is used to generate energy. Red blood cells contain a heme or iron component that binds to oxygen so that it can be transported. Without the iron molecules, oxygen could not be attached to the blood cells and the body would not be able to produce the energy necessary for life. Iron is an essential mineral, and failing to get enough from your diet can lead to a condition called anemia, which causes weakness and fatigue. This mineral is primarily found in the blood, and it is also stored in your liver, spleen, bone marrow and muscles. Nerve and Muscle Function: Potassium is found in bananas, dates, tomatoes, green leafy vegetables, citrus fruits and legumes such as peas and lentils. This nutrient is important to keep muscles and the nervous system functioning normally. Potassium helps to maintain the correct water balance in the cells of your nerves and muscles. Without this essential mineral, your nerves could not generate an impulse to signal your body to move, and the muscles in your heart, organs and body would not be able to contract and flex. Immune Health: Some minerals such as calcium are needed in large quantities, while others such as zinc are only needed in trace amounts. Zinc is an essential mineral that is important for keeping your immune system strong and helps your body fight infections, heal wounds and repair cells. KidsHealth notes that eating meat and legumes such as beans, peas and lentils will give you sufficient amounts of zinc. Selenium is also needed in small amounts for immune health. A deficiency of selenium has been linked to an increased risk of heart disease and even some types of cancers. Importance of Minerals in Aquaculture: Health and performance: Organic trace minerals are more bioavailable than inorganic trace minerals, meaning that they are better absorbed, stored and utilized by the animal. A fish that is healthy and performing optimally leads to a stronger and more robust animal that is less vulnerable to stress throughout the entire production cycle. The modern management of mineral nutrition can be accomplished with organic trace minerals at significantly lower levels than inorganic trace minerals while still improving fish performance and reducing mineral excretion into the environment. We call this innovation Total Replacement Technology™. Our highly bioavailable trace minerals Bioplex® and Sel-Plex® (zinc, manganese, copper, iron and cobalt*) play vital roles in supporting fish immunity, encouraging growth and supporting reproduction. In research conducted with Trakia University and the fish farm Nomicom in Bulgaria, it was observed that Bioplex® provided a considerable increase in weight gain and a decrease in feed conversion ratio. These results indicate that the use of Bioplex minerals in fish feed formulations have a positive impact on feed efficiency, which results in higher profitability for the farmer. Water quality: The importance of bioavailable minerals extends beyond animal health and performance and into the environment. If minerals are not properly utilized within the animal, they will be lost to the environment, negatively impacting the water quality on the farm. Recent trials have focused on the use of Alltech’s Aquate® premix, which contains Bioplex trace minerals, in fish feed diets. These minerals are chelated to organic molecules, which have been shown to interact less with each other in the digestive tract and are also less sensitive to the inhibitory action of other compounds because of their reduced solubility in water, therefore improving digestion. Because these minerals dissolve less in water than other types of minerals, it is easy to filter them out, keeping water fresh. Tastier, more sustainable fish: Understanding how a fish responds to nutrition on the genetic level can increase animal health and welfare while also helping the animal to meet its full genetic potential. This results in more efficient production through nutritional programming for tastier, more nutritious fish. By producers bringing improved nutrition to the table, consumers reap the benefits of a functional food that bridges the gap between what is on their plate and their health. Metabolism: Fish require the same minerals as terrestrial animals for tissue formation, osmoregulation and other metabolic functions (Lall, 2002). However, dissolved minerals in the water may satisfy some of the metabolic requirements of fish.They are essential for the proper function of cells, tissues, and organs. Some minerals, such as iron, make up part of many proteins and enzymes in the body. Others, such as potassium, help to produce proteins from amino acids and are involved in carbohydrate metabolism. Disease resistance: Protein plays a role in the body's immune system, especially for healing and recovery. ... Vitamin A helps regulate the immune system and protect against infections by keeping skin and tissues in the mouth, stomach, intestines and respiratory system healthy Osmotic balance: Minerals play a key role in the maintenance of osmotic pressure, and thus regulate the exchange of water and solutes within the animal body.Minerals play a vital role in the acid-base equilibrium of the body, and thus regulate the pH of the blood and other body fluids. Growth and survival: Maintaining the right level of water in your body is crucial to survival, as either too little or too much will result in less-than-optimal functioning. Several minerals are key to regulating water balance in different compartments of the body; the most important of these are sodium, potassium, and chloride. Conclusion: Minerals are necessary in aquaculture which involves in various biochemical processes at entire body.Minerals are essential for fish and these play a crucial role in the not mal metabolism and life processes. The minerals are required in extremely small amounts in the diet but in excess they cause toxicity. In deficient condition, growth is retarted in general, and impairs normal metabolism in particular. It is also a matter of concern about the potential causes of conditioned trace element de ficiencies such as food processing meth ods, dietary interactions, disease condi tions and genetic disorders. Fish can ab sorb part of the required minerals directly from the water through gills or even through their entire body surface. The minerals absorbed from water do not meet the total requirement and a certain supplementation through the diet is re quired whether in the natural food or supplementary feed. Once this requirement is met, the normal growth, survival ensured. from the Aquaculture Authority. It has accordingly been decided by MPEDA to sanction subsidy and release it only to those farmers possessing the Aquaculture licenses.