Possible Clues:

• Haul up rotten fish
• A small fish - bad one
• Just a bit
• Light touch, as with a paintbrush
• Apply with a swab, e.g.
• The sort of fish that may turn rotten, and that's flat
• Fish; a small amount
• Cologne quantity
• Bit of ointment, e.g.
• Fingerprint - fish