Depending on your local laws, it maybe illegal to take these fish from the wild I would check with your local wildlife protection agentacies.
If you are able to legally collect them, I would put them in quarrintine checking them for obvious parasites such as leeches and fish lice, and run some internal parasite medications to remove any worms etc the fish maybe harboring.
If you do all of this and then down the track decide you dont want them, DO NOT return the fish to the wild, there is every chance after being in your tank with possibly other non- native fish that they have become carriers for diseases that the wild fish populations have no natural defences against.