I would not agree that they should be areas, but only a node where the "fishfarm" symbol should be rendered as their location can vary a bit. Many fishfarms also have several locations where it moves the "cages" in between. In Norway at least, the company running the fish farm have to obtain a license for each such location, and it is prohibited to anchor the "cages" in other locations. --Skippern 23:17, 3 December 2008 (UTC)
I was also thinking of proposing landuse= fishfarm, but from another background. Here in germany we have small ponds to grow sweet water fish like carps. These ponds are mostly not natural but maintained by man and private property. You can't swim there. Of course these ponds are areas. If you could add these ponds to your definition I support this tagging proposal.
--Warlock74 16:17, 27 December 2008 (UTC)
@Thomas Wood: I think landuse= fishfarm is OK. As far as I understand landuse this tag is intended to indicate the usage of the surface of the earth. And a fishfarm is definitely a usage. With landuse= basin and landuse= reservoir there are even two tags in map features which have a relation to water. Why do you think this tag is not OK and what would you recomend instead? --Warlock74 13:50, 10 January 2009
Basically I think there are two different cases: using a fishfarm to precisely denote an artificial pond is correct. BTW, I checked that some weeks ago, there are tags to mark a lake or a marsh but not a pond, let alone an artificial one (which should be differentiated, IMO). What a «pond» is is not clearly defined either. Sometimes people use the size or depth criterion, but also the waterproof bottom criterion (natural ponds do exist)
Back to the subject: are most artificial ponds used as fishfarms or sport fishing ? Otherwise they can be basins or reservoirs… If there isn't a wide use of artificial water areas for other purposes we may not need a tag for ponds.
The second case are fishfarms in the sea (or a lake). It would be possible to tag exactly the contour of each structure, however for most mappers this would be highly impractical. Moreover they can move slightly due to wind or water flow or just be displaced by the owner. Therefore an area that denotes the presence of fishfarms in that area is needed. --Pshunter 08:31, 4 February 2009 (UTC)
@Thomas Wood: Why use another tag other than landuse=* and which one? I use landuse=fishfarm for an artificial pond used to grow fish. As such, it is similar to landuse=farm. --Segatus 10:39, 6 June 2010 (UTC)
I think this proposal should be dismissed, and landuse=aquaculture (http://wiki.openstreetmap.org/wiki/Proposed_features/Aquaculture) Should be used instead. I think the tag should be used on nodes as well as areas. On the seacharts I have seen, the "aquaculture" has been drawn as an icon, therefore used on a node in our context. --Stoffix 22:30, 18 September 2010 (BST)
What complicates things, is that a fishfarm (pond) doesn't come alone. At least in our area, a typical fishfarm is a private property, fenced, very often in a forest. A stream passes through it, and this stream is dammed to form an artificial pond. Inside the fence there is usually also a small house of wood, a barbecue place and a picnic table to eat the fish from the pond. Now it's time to reach a decision, otherwise people (including me) will just tag as they think best. --Segatus 17 September 2011 (UTC)
In India, there are a few hundred sq.km. of artificial salt water fish farms. A typical farm is half a square kilometre. The water is drawn from the sea. Also, there is little chance of using that areas for other purposes. On bing maps the residential areas look small islands. These areas are currently tagged as natural=wetland. I plan on using landuse=fishfarm. --Chaitanya 6 August 2012 (IST)