I think most breeders operate that way. There is the cull, and the keeper fish. As you know, they cull first for deformities and undesirable and the fish are destroyed. But future culls soon turn towards, live or die to sell now or sell later. The tateshita are colored up and not treated or housed near as well as the tategoi. Often they are outside under bamboo shades while the better siblings enjoy indoor heated facilities.
At this economic level ' tategoi' means 'will be worth more next year'. Afterall , why would a farmer sell something that took a lot of time, work and effort to create and then sell it at 1/4 what all his instincts and experience tells him it will be worth next year. These fish are for sale- if you are willing to pay up. And it is an escalating scale because just like a guy who graduates last in his class at medical school, he is still called Doctor. There is a theoretical line where the best tateshita is not too far from being the worst tategoi! As someone else said here- one man's tategoi is another man's tateshita when we use tategoi as a generic term. This is why I sometimes bristle when 'jumbo tategoi' are sold for outrageous prices. the term tategoi has been worked into forced grown fish. Some are tategoi and some are tateshita. But they ARE all big!
I guess the inference is that they will all get to be a meter long and they have that potential? As if--
The REAL tategoi ( or the mythical version of the word) are the rare fish that show traits or 'something' that makes the fish a 'keeper' for more personal reasons within the breeder. Maybe as a future brood fish, maybe a fish that could be, at age six, his 'lottery ticket' to the 'Show'. Or maybe a fish that works out in a breeding experiment and lets the breeder know he is on the right track. Or maybe a fish that peaks curiosity within the breeder regarding a new pairing. These fish are not for sale.
This is why 'tategoi' only has meaning within the context of the conversation. That is also why ' potential fish' is the best interpretation I have heard so far as it covers it all.