hey D i know this is a long shot, but you could go pick yourself up a crayfish trap (they sell them at Sportco in Fife) then just drop it in your nearest river and nab up any crayfish you can. my buddy has done it in some rivers and its not illegal to harvest them, just to keep them alive. however the exception to the rule would be finding a WA native species, theres only one or two i think. might be hard but you can keep those alive np. also if your interested id be happy to catch you all the snails i can out of my 10g tank. i literally just killed 100 or so before reading this post. GL with whatever you choose, maybe breed cherry shrimp also?