So, from my observation of the Shark Tuna window in Costa Del Sol:

I identified 15 opportunities to catch the fish in question.

I had ONE eligible bite, which failed (at appropriately geared level 90)

I had 8 silver sharks from a variety of large fullmoon sardines and Mooch II when available

I had 6 fullmoon sardines, that were not large, and Mooch II was not available

This is not a worthwhile experience. It's far too many layers of RNG. Ultimately, when a player catches these fish, they cannot reasonably claim any input besides they had enough gathering/perception, and they were fishing at the appropriate time/weather, That's it. It falls short of what I'd consider actual gameplay.

The solution(s) seem fairly obvious.

Get rid of Mooch II. Large fish are acting as pseudo-HQs, It's unnecessary. Mooch with *any* fish will still require the RNG of time/weather as well as actually getting the eligible fish to mooch with, as well as getting the correct catch from the Mooch.

Fix Fish Eyes: Longer duration/Persistent duration, lower GP cost, Makes only timed fish catchable for duration.

Introduce a threshold in gathering/perception where fish cannot get away.

Yes, I know, nobody forces people to fish. It's not mandatory for progression, but at the same time, don't make it this unwelcoming for people that choose to do it.