Here is my take. Right after ice out I crappie fish in the dewatered sections of the canal. Obviously these fish were in shallow water all winter long. Even when its dewatered, there is current and rarely is the ice very thick. In addition to the crappies, I catch alot of smallmouth bass, bluegills, largemouth and pike (not on purpose, but they hit my crappie jigs. This time of year there are bullhead fisherman doing real well in the drained areas.
This is in the Macedon / Fairport areas so I don't know about areas west of Fairport. The locks seem to hold more water. I would think any areas along the canal that have depressions where water may be sliightly deeper holds fish.
Beginning in Palmyra to Newark, the canal does not get dewatered so I'm sure there are alot of fish that end up there once the canal is lowered, then disperse when the canal is filled.