Will fish populate artificial underground canal

dwarf-fortress

  1. If I channel to make an artificial underground canal or pool, fed by a natural river (and disappearing at the edge of the map), is there a chance small fish (as I understand it, vermin) will populate the canal so that I can fish from it?

  2. What if I let the water run through floor grates or wall grates to keep out crocodiles? As I understand it, this will definitely keep out large fish (creatures, as opposed to vermin) like carps. But what about small fish? I.e. do vermin pass through the floor grates? Or, on the other hand is it possible that the small fish will spontaneously spawn in my artificial pool/canal?

Of course I could build a walled off area with floorgrates over the river, this would let my fisherman fish safely as well. but it's less beautiful and I thought the grate over the river would be more vulnerable to building destroyers.

Best Answer

  1. Yes, water creatures can swim from natural rivers into any connected bodies of water including those dug out by your dwarves.
  2. I believe bars, grates and fortifications all let water flow but keep creatures out, including vermin at present*. The idea for allowing vermin/small creatures to pass through bars (but not grates) has been floated in the past, but to my knowledge this has never been implemented.

Also note this bug: dwarves and creatures can sometimes be pushed through grates/bars/fortifications by water flow, though in my experience this is pretty rare.

*EDIT: @Daenthy correctly notes that vermin can spawn spontaneously in habitats that support them, so vermin may still turn up in your "secure" water sources.

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