I did it! after 3 tries, caught 1671 fish at the end.
This could 100% be a NES cartridge, and one I'd be happy to own as the game is very fun. The look and animation of the bear, bird and cat when attacking and winning are pretty much perfect, so are the speeds of everything and so is the difficulty of the game, I enjoyed the game a ton in part because you eventually need a carefully planned placement to win with just the perfectly appropriate room for little mistakes here and there.
I guess selling at only half the cost (rather than 3/4 or something) means it might not help you and you may at some point realise you're condamned to lose sometimes later into the current run while you're still only near the beginning, which happened during my second try and might not feel great to everyone, yet in my case I actually appreciated the adrenaline as I was constantly on a razor's edge, I ended with a bit more than 1400 fish caught and it was actually a fun run.
Awesome game!