The main difference is now that the check for walls is only done closer to the fish and, to compensate lacking foresight, walls trigger stronger intention to turn.
Additionally, wall vision works slightly differently now, because it's not one vision set (angle) but two distance sets (left: close/far, right: close/far). This
should enable a wall being both left and right (e.g. when swimming in a tunnel) and hopefully lead to a bit straighter trajectory in such cases.
Also, fishes now don't swim 100% straight when they have no sensory input. That looked rather strange in a huge ocean.
PPS: also reduced slimness of fish. Very slim fish looked stupid.