What do the longfin eel (tuna) look like, what do they eat, where do they live. This site provides answers to these questions and many more.
http://www.longfineel.co.nz/lo...
This site talks about what sort of features the eel environment needs to have.
https://www.niwa.co.nz/te-kuwaha/tools-and-resources/tuna-information-resource