The present invention provides a process for preparing high nutritive fibres from fish proteins which comprises grinding whole fish or fish pieces in the presence of water and then adding alkali to the ground fish. The alkali/fish mixture is then heated and cooled and the cooled mixture is then passed through a colloid mill thereby eliminating solid particles to obtain a protein solution. The solution is then injected through a spinneret into an aqueous acid medium causing the coagulation of the proteins into fibres. The fibres are then washed, set by heating and then neutralized. The fibres obtained by this process are also described.