They sure are fast growing. I have had my barra for close to 6 months now and hes becoming a little monster. The jardini arnt available from my LFS until around Christmas and will only be 8-10cm. I'm worried that my barra will harass and possibly eat the jardini as he will be probably close to 30cm by that time. I'm thinking I will have to grow the jardini out a little before introducing him as ive watched my previous barra eat fish nearly half their size. It will be an interesting combo my but really cool if it works.Barramundi are a very fast growing fish. Mine went from an inch to almost 12" in less than a year, and he's not slowing down. The only issue with the aro being bigger is that jardinis are usually pretty mean. I'm not sure about leichardtis but I know people who have had jardinis that had to be kept alone. It certainly could work and I think it's worth a try. I've had my barra with far more interesting and odd tankmates so it would probably work.