Fish, man and environment: strategy of survival"

Komolafe, Olaniyi Olusola (2019-08-20)


Fishes are aquatic a nimals. They are a part of the numerous coldblooded craniate vertebrates such as the bony fish like Tilapia, catfish, sturgeons, eels, mackerels and cartilaginous fish (shark, ray, chimaera) whose skeleton is largely composed of cartilage. Other groups of fish include jawless fish, (Agnatha) such as Cyclostomes and other extinct related forms which are primitive vertebrates. Fish species can be identified through external morphological features. These include: body shape, scale size, pattern of colours, scale count, relative position of fins and the number of fin rays. Other defining physical features include the standard length, total length, head length and width. Fish species are found in rivulets, streams, rivers, ponds, lakes, lagoons, seas and oceans. In some odd places all over the world, different fish species have adapted to various environments such as high mountain lakes in high temperature tropical waters and in regions where the temperature is below zero. Nearly all fishes hide. Some fishes hide to escape from their enemies while some hide to prey on food or for both purposes. Some of the fishes also camouflage while others hide by similar colouring (food fish) transparency or countershading (mud catfish) and by changing their colours. In every other parts of the world, fish species are used as food, thereby contributing to a high percentage of protein supply to individuals. They are also used as recreational animals whereby anglers derive joy in angling. Some people use them for sports and festivals as in the case of Argungu Festival in Kebbi State of Nigeria while others derived joy watching them in tanks, concrete aquaria glass etc. Some fishes are used to control pests and weeds as observed in Tilapia species. Fishes are used as scientific specimens in different fields such as in Animal behaviour, Histology, Anatomy, Morphology, Embryology and even as indicators of polluted environment. Other uses include fish oil for making soap, fish skin for leather works, fish scales for beads and ear-rings. The eyes and head of fish contain polysaccharide which helps to keep the blood vessels and skin flexible. The bone contains calcium while the skin contains vitamins A and B2. Fish tissues also contain high grade of protein and vitamins. Inland Water Bodies and Surface Area in Nigeria