Sunil, when the garbage cans we used were put in the water, they floated horizontally but only about 1% or less was at the surface. For example, an iceberg floats but most of it is under water.
We didn't sink our cans because when the can is at the surface, it can be uprighted quickly before the bullhead swims away. If on the bottom, I suspect the fish would swim off before the container reached the surface.
