Appearance
Ōnamazu, the Sewer Catfish
Boss
| Stat | Value |
|---|---|
| Health | 2,200–43,500 |
| Power | 25–521 |
| Defense | 11–200 |
| Speed | 9.5 m/s |
| Aggro radius | 14 m |
| Material |  Ōnamazu's Barbel |
Health, power and defense: from the lowest to the highest level it is met at. Inside a gate the monsters take the level of the first one in, and their stats and experience follow that level; health and power grow by half for every further party member.
Where
Attacks
| Attack | Shape | Range | Wind-up | Cooldown | Damage | Effects | Warning |
|---|---|---|---|---|---|---|---|
| Catfish Bite | Melee strike | 3.6 m | 0.34 s | — | 140% of power | — | No |
| Barbel Lash | Cone, 120° | 8 m | 0.62 s | 7 s | 200% of power | — | Yes |
| Mudquake | Area around itself, 7 m | 6 m | 0.79 s | 12 s | 200% of power | Stunned 1.5 s | Yes |
| Tidal Spout | Areas under up to 3 players, 3 m each | 20 m | 0.74 s | 9 s | 180% of power | Slowed 2.5 s | Yes |
Below 60% health
Speed ×1.15, power ×1.2. Summons 2× 
Sewer Kappa.
| Attack | Shape | Range | Wind-up | Cooldown | Damage | Effects | Warning |
|---|---|---|---|---|---|---|---|
| Catfish Bite | Melee strike | 3.6 m | 0.34 s | — | 140% of power | — | No |
| Barbel Lash | Cone, 120° | 8 m | 0.62 s | 7 s | 200% of power | — | Yes |
| Mudquake | Area around itself, 7 m | 6 m | 0.79 s | 12 s | 200% of power | Stunned 1.5 s | Yes |
| Tidal Spout | Areas under up to 3 players, 3 m each | 20 m | 0.74 s | 9 s | 180% of power | Slowed 2.5 s | Yes |
| Great Flood | Area around itself, 9.5 m | 9 m | 1.02 s | 16 s | 270% of power | Slowed 3 s | Yes |
Below 25% health
Speed ×1.3, power ×1.4. Summons 2× 
Nure-onna.
| Attack | Shape | Range | Wind-up | Cooldown | Damage | Effects | Warning |
|---|---|---|---|---|---|---|---|
| Catfish Bite | Melee strike | 3.6 m | 0.34 s | — | 140% of power | — | No |
| Barbel Lash | Cone, 120° | 8 m | 0.62 s | 7 s | 200% of power | — | Yes |
| Mudquake | Area around itself, 7 m | 6 m | 0.79 s | 12 s | 200% of power | Stunned 1.5 s | Yes |
| Tidal Spout | Areas under up to 3 players, 3 m each | 20 m | 0.74 s | 9 s | 180% of power | Slowed 2.5 s | Yes |
| Great Flood | Area around itself, 9.5 m | 9 m | 1.02 s | 16 s | 270% of power | Slowed 3 s | Yes |
Drops
| Drop | Count | Chance per kill |
|---|---|---|
 Uncommon Mana Crystal /  Rare Mana Crystal /  Epic Mana Crystal /  Legendary Mana Crystal | 1 | 98%–100% |
| Ōnamazu's Barbel | ×1–3 | 30% |
 Ōnamazu's Shotgun /  Ōnamazu's Scale Cuirass /  Ōnamazu's Mud Boots | 1 | 4.95%–5% |
 Return Crystal | 1 | 5% |
 Mythic Mana Crystal (Mythic) | 1 | 0%–2% |
 Ōnamazu's Mantle (cosmetic) | 1 | 1% |
| Ōnamazu's Shotgun / Ōnamazu's Scale Cuirass / Ōnamazu's Mud Boots (Mythic) | 1 | 0%–0.05% |