The Nyishi are agriculturalists who practice jhum, known as rag in Nishi, which is a form of shifting cultivation. The principal crops raised include paddy (unmilled rice), tapio (maize), mekung (cucumber), takie (ginger), aange (yams) and temi (millet). Rice is the staple food of the people, supplemented by fish, meat of various animals, edible tubers and leafy vegetables. Before a Western market economic system arrived, they used a barter system. They greatly valued the generalized reciprocity and also balance reciprocity in their economic system. A locally-made drink known as apong (the two types of apong: pone, made of rice, and poling which is made of millet) is served at every social gatherings and important events. The Nyishis are typically fond of it. Traditional ways of preparing them include steaming, roasting and smoking. Recently they have been forced to move towards a market based exchange economy.

Prior to entry of currency the traditional economy was always centred on the mobilization of local limited resources and meeting up the local demands. But after entry of currency the economy it is now, both centred in both side. At the same time all economic activities are determined by the evolved socio-cultural and religious belief of the people. Agriculture has been the mainstay of the Nyishis since the time immemorial. The shifting cultivation by slash-and burnt method called Tumph Rongo (jhum) is the type of agricultural is popularly practice by almost all tribes of the state. Now, the people has adopted wet paddy cultivation almost in all areas.

Generally, the Nyishi practice three types of cultivation on the basis of ripening pattern of the crops. First one is called ‘Teming Rongo’ – field proximity to the house on lightly manure land, where early ripening ones are grown. The second is ‘Rekhte Rongo ‘ – a distance clearing, where the bulk of late ripening crops are grown. Third is wet Seppa Rango paddy cultivation. A typical Nyishi jhum field is used for growing variety of crops based on mixed cropping pattern. The important crops include rice, maize, millet, .potato, mustard, pumpkin, cucumber, ginger, chilly, sugarcane, vegetables of different varieties etc. Labour mobilization is always made on the basis of mutual reciprocity called Rey Angnam. Manpower can be mobilized either individually or in group, depending on the nature of work. A community service is also arranged for those needy villagers on self-help basis.

Along with agriculture and allied activities, the Nyishis are expert in handicrafts i.e. weaving, cane & bamboo works, pottery, blacksmith, wood carving and carpentry etc. Traditionally, the basic purpose of producing these craft articles was to meet the demands of the family. Agriculture, livestock breeding, hunting and fishing sustained the Nyishis to maintain a high degree of self-sufficiency in so far as food is concerned. However, the additional requirements such as cloth, utensil, salt etc. are obtained through barter trade-evolved since and immemorial, among themselves and from their neighbours. Early Nyishis confined their trading activities amongst the tribesmen themselves and with the people across the northern border called Nyeme chanam i.e. trade link with the Tibetans.