Loch Fad
{{Use dmy dates|date=April 2022}}
{{more citations needed|date=December 2018}}
{{Infobox body of water
| name = Loch Fad
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| location = Isle of Bute, Scotland
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| coordinates = {{coord|55.806|-5.074|type:waterbody_region:GB|display=inline,title}}
| type = loch
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Loch Fad is a freshwater loch on the Isle of Bute in Scotland.
Its name means "long loch" in Scottish Gaelic. It lies on the Highland Boundary Fault.
Its surface area is {{convert|71|ha}}, fairly large for a freshwater loch on an island in Scotland.
It is the site of one of the largest rainbow trout cage farms in the UK.{{cite journal |last1=Phillips |first1=M. J. |last2=Beveridge |first2=M. C. M. |last3=Ross |first3=L. G. |year=1985 |title=The environmental impact of salmonid cage culture on inland fisheries: present status and future trends |journal=Journal of Fish Biology |volume=27 |issue=sA |pages=123–137 |doi=10.1111/j.1095-8649.1985.tb03236.x}}
In 2018, it was used for tests of Donald Campbell's boat, Bluebird.