Change the angle first
Surface glare strengthens when the camera meets the water at a shallow reflective angle. Move slightly higher, lower or sideways while keeping stable footing; shade the lens when possible.
A polarizing filter can reduce some reflection but may also change brightness and color. Record at least one unfiltered frame for comparison.
Preserve context
Clean the lens, tap focus on the eye or flank mark and take a wider habitat view. Avoid digital zoom when moving closer would threaten safe footing or disturb the animal.
Keep the original file. Crops and exposure adjustments are useful for presentation, but identification reviewers should be able to inspect the unedited evidence.