Oarfish — 800G
One of the rarest fish in mid waters, appears only at night. Its body is extremely long (up to 5m+), requiring 4-5 consecutive hits to capture. It swims in a wave-like motion — the best attack window is when it turns. Use an advanced harpoon gun + booster for pursuit.
Giant Squid — 1200G
A legendary deep-sea creature found at 150-250m depth, only at night. Extremely difficult to capture: it has numerous tentacles and will actively attack. Bring at least 3 Med Kits. Use an advanced harpoon gun to attack tentacles one by one, then target the head once tentacles retract. Expect about 15 effective hits.
Sea Dragon — 1800G (Legendary)
Requires 80%+ fish guide completion to appear in the deep hydrothermal vents. Night only, approximately 30% spawn chance. The Sea Dragon is one of the hardest creatures to find — but also the most valuable collection target. You can photograph it to complete the guide entry without capturing.