If i wanted to set one up, would I be able to go grab some crabs, mangroves and some small schooling fish from the estuary just down the road legaly? I have also seen what I think is called a "mantis shrimp" with big claws and is quite colourful. Would I need a raised part of sand so it creates an island effect? Would I be able to use water down from the estuary aswell?

thanks

I think the regulations in regard to taking anything from the sea are quite strickt so be carefull, If you are after somthing like mud skippers then yes you do need to create a shaw although i think they can live happily in a tank without one