There are some 24"-30" I've seen floating around. I can surely tell you that a 500 is but a speck of water to a 30" Goliath. They need a lot of open swimming room and they damage themselves and can go into shock very easily. Good luck with your search and post pics.
that is so true... well said about the "speck of water". in my experience, a 12 inch ATF (VATF or GATF)is "cramped" in a 700+ gal tank... 8ftx4ft... yes, its big enough, it lives, but its cramped. For an open water predator like that, I would think a 30" fish should be in minimum 24ft long tank. and even that would be limiting.
Yeah, sounds stupid, I know... tank nazi here. But just watching them swim and how they behave, they need LOTS of swimming space. we CAN keep them in smaller tanks of course, but SHOULD we?
this is my reply to all this...I love ethical debates
this opens up a whole can of worms. ethics. if that is the case, almost all asian fish keepers in Japan, Hong Kong, Taiwan should be banned from keeping large fish. But the fact is if it wasn't for some of them, we wouldn't have some of the crazy rare fish you see here.
This has been brought up many times in the past, no matter how large of a tank you have its not big compared to the smallest pond or lake. Unless you keep killis, guppies and bettas.
What is the ethical basis of how we should determine the fish we keep? The ability for a fish to swim, to feed properly, to breed? The purpose of all living beings on this earth is for survival of the species, to breed. However, many of the xxl fish cannot breed in captivity, so then what?
How about if they can eat, swim comfortably, then its ok? Would their life span be longer or shorter in captivity? People use to attack me for keeping a bumble bee grouper. Well if it was in the wild, most of the larvae and fry would be eaten before reaching any size at all, and millions are being consumed around the world.
So I think at the end, the answer is all subjective., its all how each individual feels about it. I draw the line at arapiama, I think it grows and grows and usually doesn't get enough food when its really big and then it gets slightly deformed. Unless you have a tank like JohnPTC's 15000 gallon, which I think is fine, since these fish do not swim like a pelagic fish.
As for african tiger fish and the original post., goliaths from my experience grow slower than vittatus, and are more timid when young, so an inch larger would be ok to keep together. As for tank size big enough, honestly, no tank is big enough, but I have seen healthy 3 feet specimens kept in a tank that is only 6 feet by 4 feet wide, the fish doesn't swim and as long as its not spooked, looks perfectly content.
Also seen 4 30" hydrolycus armatus in a 180 gallon tank, side by side, no agression, perfect body and shape. Then these are all not in the US...like my rant?