Yes, fishing can be done in sustainable ways. Sustainable fishing ensures that the populations in the ocean and rivers will be there in the future, since is important to maintain the wildfife of the aquatic species to guarantee a healthy ecosystem. For decades human population have fished to feed their communities, but the problem with overfishing is more related to the commercial fishers and the technology that takes more than necessary number of aquatic organisms. Fishing in a clean way is made by using technology with biological knowledge to make possible the balence between the humans needs and the maintanance of the aquatic species, being not take more than necessary and in the right times (do not fish during breeding season, for example).