The Parable of the Net in verses 47-50 teaches of the future & final judgment of the Kingdom of Heaven as a time of separating two groups of souls. Parables of this kind are not spoken by Jesus to satisfy the curiosity of those who desire to know about the end times prophecy. Jesus teaches this parable (and other judgment parables) to alter life in the present. Jesus told parables to confront people with the character of the Kingdom of Heaven and to invite them to participate in it and to live in accord with it.
This parable teaches the final separation between the good and the bad fish ... separation of the rotten and vile souls from the good and fresh souls.
The spiritual net of the Kingdom of Heaven drags the souls of the world to gather up all in its path. Nothing escapes this drag net. Nothing will escape the Kingdom of Heaven as judgment comes. We are all right now caught up in this dragnet. No one is free from its depth.