hey Dingo, marron are extremely difficult to grow in AP, beleive me I am the master of marron *frack* ups, really you can have about 8 in a 3000lt tank, marron are territorial and like a bit of space, they will try to escape if over crowed and will more than likely die trying, generally they are not vicious and will not fight each other, marron take around 3 years to get to size as well, they eat a small pellet a week compared to yabbies that eat one a day, in the same tank I have around 200 yabbies which fight to the death regularly but for a feed yabbies are best option.
In saying that my Mate the GWH has secured me about 20 blue marron 8cm long for 60c each
he actually got 3000 at this price so I am again having a go with Marron for breeding purposes
and yes the best of all to eat but are also a good source of gout, beleive me 
As I can easily obtain both marron(locally) and yabbies(visiting kalgoorlie in a few weeks) it is a tough call, only having a 1000lt courtyard system would it be better to have them in the tank with the 20 trout I have or modify the system to encorporate 60lt tubs for them.
