I am currently building an aquarium (1350 X 510 X 700) out of plywood. It was meant to be an upgrade for my octopus, but four days into the build my octopus had an unfortuanate encounter with my needle urchin. Seeing as the octopus was small, tentacles only 10cm long, the urchin won the battle. Now i sit with an almost complete tank and have no idea what to put in it. I live in Cape town and would prefer to stock the tank with local species. Any ideas on what species of invertebrates do well in aquaria?