“The best road maps to human bodies lie in the bodies of other animals. The simplest way to teach students the nerves in the human head is to show them the state of affairs in sharks. The easiest road map to their limb lies in fish. Reptiles are a real help with the structure of the brain. The reason is that the bodies of these creatures are often simpler versions of ours

“Ancient fish bones can be a path to knowledge about who we are and how we got that way. We learn about our own bodies in seemingly bizarre places, ranging from the fossils of worms and fish recovered from rocks from around the world to the DNA in virtually every animal alive on earth today. But that does not explain my confidence about why skeletal remains from the past—and the remains of fish, no less—offer clues about the fundamental structure of our bodies.”

Neil Shubin; in his ‘Your Inner Fish’ book

Fishes are the most numerous of the vertebrates, with estimates of around 20,000 recent species, although guesses range as high as 40,000. Thus, not only are there many different fishes but they come in many different shapes and sizes.

At present, more than 70 percent of the earth’s surface is covered with water. As an aquatic animal fishes live almost wherever there is water, both on the surface and in the surface-connected subterranean waters. They occupy everything from Antarctic waters below freezing to hot springs of more than 40°C, and from soft, fresh water to water saltier than the seas. They are present in sunlit mountain streams so torrential that neither man nor dog can wade or swim them, and in waters so quiet, deep, and dark that they have never been inhabited by other vertebrates or thoroughly explored by man. Their vertical range of distribution exceeds that of any vertebrates. Fishes range from approximately 5 kms above sea level to some 11 kms beneath it.

Life in earth was first appeared in aquatic environment. In this way, presence of fish on earth antedates man’s ape-like ancestors by some 500 million years, and all other vertebrates by more than 100 million years. Without piscine ancestry, man might never have evolved. Many features of life ways and structure of man were originated or were already present aeons of time ago in fishy ancestors! These features include the ground plans and basic functions of the ten organ systems, including such striking features as sight, internal fertilization, intrauterine nourishment (including placenta), live birth, and, presumably, learning and memory.Fish have had a role in culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies.

Fish and fish relatedorganisms such as plankton, microbes, seaweed, shellfish (shrimp, clam, lobster etc.)etc. are indispensable part of ecosystem.Destruction of aquatic environment globally due to anthropogenic activities has stood as a crucial concern for human.

Growth in knowledge of fishes has resulted from our lasting curiosity about nature and from our need for information concerning species used for commerce or recreation. People of Iceland has been utilizing fish for any kind of daily need e.g. food, medicine, clothing, pet feed, fuel etc. International trade plays a major role in thefisheries and aquaculture sector as an employment creator, food supplier, income generator, and contributor to economic growth and development, as well as to food and nutrition security. In 2014,fish and fishery products represent one of the most-traded segments of the world food sector, with about 78 percent of seafood products estimated to be exposed to international trade competition. For many countries and for numerous coastal and riverine regions, exports of fish and fishery products are essential to their economies, accounting for more than 40 percent of the total value of traded commodities in some island countries, and globally representing more than 9 percent of total agricultural exports and 1 percent of world merchandise trade in value terms. Trade in fish and fishery products has expanded considerably in recent decades, fuelled by growing fishery production and driven by high demand, with the fisheries sector operating in an increasingly globalized environment. In addition, there is an important trade in fisheries services.

Bangladesh is blessed with huge open water resources with a wide range of variations in nature. 260 freshwater fish species, 475 species of marine fish, 24 prawnand 36 shrimp species, and also more than 190 species of macroalgae has listed yet.So,fish and fisheries are the indispensable part of life and livelihood of the people of the country since immemorial time.It is an element of Bangladeshi cultural heritage.Fisheries sector has been playing a vital role in alleviating protein shortage, providing jobs for unemployed youth, earning foreign currencies and socio-economic development of Bangladesh. At present Bangladesh has placed 4th in country wise inland aquaculture production.Recently, by verdict from the United   Nations   Permanent   Court   of Arbitration  (UNPCA)  and  ‘International Tribunal  of The  Law  on The  Sea  (ITLOS)’ on  the  maritime  demarcation  between  Bangladesh and India, and Bangladesh and Myanmar, Bangladesh has achieved  absolute  sovereignty  on  vast maritime  area,  on  overall,  approximately 111,631  square  kilometres  was  assigned to  Bangladesh  of  the  relevant  area  with Myanmar, ( approximately 171,832 square kilometres  to  Myanmar),  and  19,467  sqkms  to  Bangladesh  of    25,602  sqkms with India. Bangladesh fisheries has apple scope of development to strengthen the national economy.