those tanks on that german website are gonna take loads of time and money!!! my crab tank has a slope of gravel with a large beach at one end and a piece of wood half in half out of water (they love it - they hide under it and even eat bits of it!) a filter with a spray bar (the water only comes a quarter way up the tank) and a load of platic plants with most of their leaves out of the water. A bit of advice from one crab keeper to another - don't bother shelling out for real plants mine ate them all in a week even the java fern. they are great little animals but beware - they make alot of waste so hold your breathe when cleaning the filter; its gonna stink!!! if you can get them (they're hard to come by) feed Hikari crab pellets mine love them - they also love boiled lettuce. hope this helps.