I just downloaded the Crayfish plugin. It downloaded successfully but then when I search for it in QGIS, it is nowhere to be found. Can someone suggest where it might be located?
After installing the "Crayfish" Plugin in QGIS it should appear in the Mesh menu
Moreover, as was already mentioned by @Mapperz a Crayfish 2D Plot is available via
RMC > Panels > Crayfish 2D Plot
You can also find "Crayfish" in the Processing Toolbox
For more details please check the official documentation.