Can be used to catch coelacanth,salmon,piranhas,leeches,Lampreys and even Trilobites after catching them they are like half taimed they wont follow you i believe but im not sure but piranhas for example can be used as under water guards if you build in a lake and lampreys to nullify radiation

These things have such a short range, makes it almost impossible to capture anything that moves. Not recommended unless you need to use it(for shadowmane etc.)