Possible Clues:

• Well, that's not fresh fish, so it's not
• Troubled in mind or body
• The fish may be first-rate, but it makes one sick
• Poorly? Don't start crying
• Though the fish is all right it may make you sick
• You may get sick of fish, even if it's first-rate
• Sickly
• Even first grade fish may make one sick
• Although first-rate, the fish makes one sick
• Start off going by sea, feeling sick