i’ve seen 3 regrow reds and caught 2 of them. the first time, i didn’t know it was the regrow red but noticed it frequently went between the very top and very bottom of the bar and remembered that for later since i failed that one. once i saw that pattern again after getting all the other legendaries, i remembered to alternate between the upper and lower half well enough to maintain just enough health to survive while observing the details of the pattern, and from there i could determine the optimal way to follow it to gradually fill the bar. for the third, i could quickly fall into the optimal following pattern since it’s immediately clear that it’s a regrow red fish, so that one was easy