For a backup/auxiliary CCSF release, I was thinking about adding some converted C2 critters to the garden box. While mulling over ideas, I came up with the idea of "patch critters," similar to patch plants but subtly different (besides what's being made, of course).
Instead of growing fruits, a patch critter agent would let you define an area where a certain critter (for example, zander fish). The patch options panel is a little different - instead of having density, growth rate, and growth plane, patch critters would have spawn rate and maximum population. Spawn rate controls how fast the critters spawn, and maximum population is self-explanatory: how many critters would be spawned before the agent stopped making them. When the critters fall below the maximum population, new ones spawn in the area.
You could technically already do something like this by screwing with patch plants, but there's a problem there. For example, let's say there's a patch "plant" agent that spawns fish. You define an area in a body of water to spawn these fish. Since the patch plant module isn't designed to create critters, it'll likely get confused and spawn another fish whenever one wanders out of the area that was defined. This would likely keep going until the agent spawned enough fish that there was always the maximum amount inside the area; most likely resulting in a body of water so full of fish you can't see anything else.
Just something I thought might be interesting/useful.