I recently made a suicide alt in order to try out the new credo and I might be very unlucky on the questrolls but every other quest recquired me to get some kind of cavefish. After a couple of hours searching through various caves I finally found a lake with fish in it but this is an old world with tunnels dug far and wide, had it been a new one I'd probably put off trying to get the fisherman credo alltogether.
Could you lower or even better remove the cavefish from the fishing credo? The credo was hard enough to get even before the cavefish.