Mazuri Platinum Bits Koi Fish Food, 20 lb. Bag

Twenty or 20 may refer to:

• 20 (number), the natural number following 19 and preceding 21
• one of the years 20 BC, AD 20, 1920, 2020

A bag (also known regionally as a sack) is a common tool in the form of a non-rigid container, typically made of cloth, leather, bamboo, paper, or plastic. The use of bags predates recorded history, with the earliest bags being lengths of animal skin, cotton, or woven plant fibers, folded up at the edges and secured in that shape with strings of the same material. Bags can be used to carry items such as personal belongings, groceries, and other objects. They comes in various shapes and sizes, often equipped with handles or straps for easier carrying.

Bags have been fundamental for the development of human civilization, as they allow people to easily collect and carry loose materials, such as berries or food grains, also allowing them to carry more items in their hands.

The word probably has its origins in the Norse word baggi, from the reconstructed Proto-Indo-European bʰak, but is also comparable to the Welsh baich (load, bundle), and the Greek Τσιαντουλίτσα (Chandulícha, load).

Cheap disposable paper bags and plastic shopping bags are very common, varying in size and strength in the retail trade as a convenience for shoppers, and are often supplied by the shop for free or for a small fee. Customers may also take their own shopping bag(s) to use in shops.

Although paper had been used for wrapping and padding in Ancient China since the 2nd century BC, the first use of paper bags in China (for preserving the flavor of tea) came during the later Tang dynasty (618–907 AD).

A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits. Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians. Most fish are cold-blooded, their body temperature varying with the surrounding water, though some large active swimmers like white shark and tuna can hold a higher core temperature. Many fish can communicate acoustically with each other, such as during courtship displays. The study of fish is known as ichthyology.

The earliest fish appeared during the Cambrian as small filter feeders; they continued to evolve through the Paleozoic, diversifying into many forms. The earliest fish with dedicated respiratory gills and paired fins, the ostracoderms, had heavy bony plates that served as protective exoskeletons against invertebrate predators. The first fish with jaws, the placoderms, appeared in the Silurian and greatly diversified during the Devonian, the "Age of Fishes".

Bony fish, distinguished by the presence of swim bladders and later ossified endoskeletons, emerged as the dominant group of fish after the end-Devonian extinction wiped out the apex predators, the placoderms. Bony fish are further divided into the lobe-finned and ray-finned fish. About 96% of all living fish species today are teleosts, a crown group of ray-finned fish that can protrude their jaws. The tetrapods, a mostly terrestrial clade of vertebrates that have dominated the top trophic levels in both aquatic and terrestrial ecosystems since the Late Paleozoic, evolved from lobe-finned fish during the Carboniferous, developing air-breathing lungs homologous to swim bladders. Despite the cladistic lineage, tetrapods are usually not considered to be fish, making "fish" a paraphyletic group.

Fish have been an important natural resource for humans since prehistoric times, especially as food. Commercial and subsistence fishers harvest fish in wild fisheries or farm them in ponds or in breeding cages in the ocean. Fish are caught for recreation, or raised by fishkeepers as ornaments for private and public exhibition in aquaria and garden ponds. Fish have had a role in human culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies.

Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin and contains essential nutrients such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells to provide energy, maintain life, or stimulate growth. Different species of animals have different feeding behaviours that satisfy the needs of their metabolisms and have evolved to fill a specific ecological niche within specific geographical contexts.

Omnivorous humans are highly adaptable and have adapted to obtain food in many different ecosystems. Humans generally use cooking to prepare food for consumption. The majority of the food energy required is supplied by the industrial food industry, which produces food through intensive agriculture and distributes it through complex food processing and food distribution systems. This system of conventional agriculture relies heavily on fossil fuels, which means that the food and agricultural systems are one of the major contributors to climate change, accounting for as much as 37% of total greenhouse gas emissions.

The food system has significant impacts on a wide range of other social and political issues, including sustainability, biological diversity, economics, population growth, water supply, and food security. Food safety and security are monitored by international agencies like the International Association for Food Protection, the World Resources Institute, the World Food Programme, the Food and Agriculture Organization, and the International Food Information Council.

Koi (鯉, English: , Japanese: [koꜜi]), or more specifically nishikigoi (錦鯉, Japanese: [ɲiɕi̥kiꜜɡoi], literally "brocaded carp"), are colored varieties of carp (Cyprinus sp.) that are kept for decorative purposes in outdoor koi ponds or water gardens.

Koi is an informal name for the colored variants of carp kept for ornamental purposes. There are many varieties of ornamental koi, originating from breeding that began in Niigata, Japan in the early 19th century.

Several varieties are recognized by Japanese breeders and owners, distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, yellow, blue, brown and cream, besides metallic shades like gold and silver-white ('platinum') scales. The most popular category of koi is the Gosanke, which is made up of the Kōhaku, Taishō Sanshoku and Shōwa Sanshoku varieties.

Platinum is a chemical element; it has symbol Pt and atomic number 78. It is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name originates from Spanish platina, a diminutive of plata "little silver".

Platinum is a member of the platinum group of elements and group 10 of the periodic table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in Earth's crust, with an average abundance of approximately 5 μg/kg. It occurs in some nickel and copper ores along with some native deposits, mostly in South Africa, which accounts for ~80% of the world production. Because of its scarcity in Earth's crust, only a few hundred tonnes are produced annually, and given its important uses, it is highly valuable and is a major precious metal commodity.

Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Consequently, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the alluvial sands of various rivers, it was first used by pre-Columbian South American natives to produce artifacts. It was referenced in European writings as early as the 16th century, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it began to be investigated by scientists.

Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Platinum is used in the glass industry to manipulate molten glass, which does not "wet" platinum. As a heavy metal, it leads to health problems upon exposure to its salts; but due to its corrosion resistance, metallic platinum has not been linked to adverse health effects. Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are applied in chemotherapy against certain types of cancer.