Well, just for it to be that buoyant tells you that something is seriously wrong with it. And for a fish to “take off” and apparently swim well (but not be many dozens of feet away before you know it) requires almost no effort for an animal that can practically do so in its sleep (most people have no clue how fast a healthy fish of that type and of that size really is). I once ran across a 2.5-foot tiger musky in a little creek, a few miles upstream of the lake where it should have been living. It too was dying, but slowly making its way downstream with the current, and in control of itself to the extent that it appeared to be hovering normally, and every now and then would appear to move normally. The thing is, that fish, in that environment, in sight of my boat, SHOULD have fled at a speed too fast for the eye to follow. I know because I once drifted up on a 2.5-foot northern pike in clear water that was about 3 feet deep, and once that fish took flight, it was simply “gone”. There was no chance of watching it swim away in spite of the clarity of the water.