Regrettably I may have to move on my large rainbow shark, he's approx 20cm and is absolutely stunning, I'm having tank issues and my other tank is just too small for him. I have no idea what he's worth or what to ask for him. He's worth his weight in gold how awesome he is though! He MUST go to a big tank and I want to check this (hope that doesn't sound rude). Dunedin. I'll also look at swapping for other (smaller) fish - we have other tanks just none big enough for him.
Also, while I'm here....have a bottle of api pH down 437ml, unopened but unused.