Cod lure and rod
Fit a Beginner Lure ($3, sold from Island 2 onward) on the long Fishing Rod and fish around the Forest island; Cod shares the top bite share of that pool with Pike and Piranha at 15.4% each.
The game data also lists Cod at 100% on an empty hook, which makes it the one creature you can target without buying anything.
Drip Cod
Drip Cod exists. Every hooked Cod rolls the normal 10% drip chance, raised to 25% after five Wishbone levels.
On the Beginner Lure that is about 65 bites per drip Cod (26 with the full Wishbone).
If the empty hook returns only Cod, every bite is a drip roll: about 10 bites, or 4 with the Wishbone. Release unwanted bites with right-click instead of reeling them in.
Cod sell price
Cod sells for $10 raw, about $15 once the Desert grill is unlocked and you cook it to its peak.
That is pocket money next to the Forest island's Goldfish ($24), so keep Cod for food and for the Fishipedia entry rather than for income.
Other catches on the Beginner Lure
| Bite chance | Price | |
|---|---|---|
 Pike | Beginner Lure 15.4% ; French Fry 20% | $12 |
 Piranha | Beginner Lure 15.4% | $4 |
 Carp | Beginner Lure 12.3% | $12 |
 Salmon | Beginner Lure 10.8% | $14 |
 Triggerfish | Beginner Lure 7.7% | $18 |
 Goby | Beginner Lure 7.7% | $12 |
 Perch | Beginner Lure 7.7% | $18 |
 Goldfish | Beginner Lure 6.2% | $24 |
 Sunfish Boss | Beginner Boss Lure 50% ; Beginner Lure 1.5% | $50 |