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IDProjectCategoryView StatusLast Update
0010135Dwarf FortressCreaturespublic2017-02-08 07:14
ReporterFantasticDorf Assigned To 
PrioritynormalSeveritymajorReproducibilityalways
Status newResolutionopen 
Product Version0.43.05 
Summary0010135: Aquatic creatures are scared of 'dangerous terrain' of deep water, and cannot swim.
DescriptionFish cannot path through dangerously deep water, they require the water level to drop low enough for them to move at about 3/7th's at which case they start air drowning. This shows that they are relying on land-pathing since land creatures scared of deep water can enter 'waist height' water of 3/7ths

Creatures with [SWIMS_INNATE] do not have the ability and require the ability to swim, fish will sit static until acted on by water pressure which trains them by forcing them to move in water. Which also allows them to not move past the dangerous terrain or recognize that the water is not a barrier.

If the creature can path onto land (via being amphibious) they will prefer to do so rather than stay in the water, acting on pathing a fish cannot do.

Related save in 'Steps To Reproduce'
Steps To ReproduceExtract from file & run the save - http://dffd.bay12games.com/file.php?id=12699

There is a river on the save with a population of tigerfish, immediately observable is that the fish have piled up at the map edge and are dying (one rotting & 1 skeletal already), waiting a while will see more fish join this pile as they try to navigate past the 3/7th's or less water which they try to path over to exit. There is a fish air drowning as soon as the save starts in that pile.

The river exit is on the left hand side of the river compared to the entrance which is on the right where water is pouring in. There are already some fish in the river who have gotten caught by the current and may start swimming very fast trying to path out towards the river exit. You might see this spontaneous swimming begin soon after observing.

Open up DFhack and inspect the fish, they will display dangerous terrain messages and in DF_soul have no or very low swimming skills.

Or

Embark adjacent to a river, all the amphibious creatures (turtles/otters) will soon move onto land because they have land legs and refuse to mingle in the water. Fish (animal class, not vermin) will remain static
Additional InformationError log:

path fail: tigerfish,1,31,155 -> 19,20,155: Id # 265:Path Goal Flee Terrain:Station None at 1,31,155 (Trying to move to a above water spot)

In the same vein a giant squid has difficulty moving through to deep water or other water tiles beneath itself below its current z level.

path fail: gigantic squid,6,83,3 -> 5,84,3: Id 0000002:Path Goal Seek Station Flood:Station None at 5,84,3

This report topic was mentioned originally by myself in relation to issue 0009853 at note http://www.bay12games.com/dwarves/mantisbt/view.php?id=9853#c36263 - Where animal men with [SWIMS_INNATE] drown because they have no swimming statistics or seem to not learn any more skills by swimming.
Tagsdrowning, fish, swimming, terrain, water

Activities

FantasticDorf

2017-02-08 07:14

reporter   ~0036271

Additional data gathered from this DF thread for testing pathing through water, concludes that creatures caught in 7/7ths or less "dangerous water" will path to a exit that is ATLEAST 20 tiles away, which is consistent with my tigerfish save example of trying to exit the dangerous water river exit to the left exhibited in the save through the low water.

When the water level drops they will move towards the 3/7th's or less and then path onto the next lower target then get caught & drown because they can't breathe air. 3/7ths is walkable for land creatures and also theoretically still covered in water so that fish can go there.

(Experiment results for pathing out of water (Read 1614 times)) http://www.bay12forums.com/smf/index.php?topic=116764.0

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Issue History

Date Modified Username Field Change
2017-02-05 05:56 FantasticDorf New Issue
2017-02-05 05:57 FantasticDorf Tag Attached: drowning
2017-02-05 05:57 FantasticDorf Tag Attached: fish
2017-02-05 05:57 FantasticDorf Tag Attached: swimming
2017-02-05 05:57 FantasticDorf Tag Attached: water
2017-02-05 05:57 FantasticDorf Tag Attached: terrain
2017-02-08 07:14 FantasticDorf Note Added: 0036271