A fish’s rarity comes from the traits it shows (hidden copies don’t count). Each showing trait scores points by its tier, and traits you see at a glance count fully while subtle ones (mouth, eyes, side fins, fin colour) count about a third.
| Trait tier | Points |
|---|---|
| Common | 0 |
| Uncommon | 1 |
| Rare | 3 |
| Epic | 8 |
| Legendary | 20 |
| Mythic | 50 |
The weighted score picks a tier (Uncommon from 60, Rare from 120, Epic from 180, Legendary from 360), with two rules on top:
- A fish is never rarer than its rarest visible trait, and never more than one tier below it.
- Any showing mythic trait makes the fish Mythic. Mythic traits only hatch from Mythic eggs.
How rare is rare?
From a dive under the ice, about 60% common, 25% uncommon, 10% rare, 4% epic, 1% legendary of traits roll at each tier; deeper zones shift the odds toward rarer fish. Diving