Fig. 3
From: The use of external electronic tags on fish: an evaluation of tag retention and tagging effects
Example of typical external transmitter placement on a fusiform-bodied fish (Atlantic salmon, Salmo salar). This radio tag has a flattened section that lies close to the body surface and is held in place by stainless steel wires through the musculature. Note that these tags have conspicuous return information, which is not problematic for adult salmon, but could be an issue for smaller fish that may be susceptible to increased predation risk