Finding Neptunium
Neptunium is Aquaculture 2's endgame material. You obtain it by fishing — specifically, you catch Neptunium Ingots or Neptunium Nuggets as rare loot from fishing. The chance is low, so you need patience and good gear. Using better rods, hooks, and bait improves your odds.
Crafting Neptunium Items
Once you have Neptunium Ingots, you can craft Neptunium tools, weapons, and armor. Neptunium gear is stronger than diamond and has unique properties (such as higher durability or special effects). You can also craft a 
Neptunium Block by combining ingots. Check JEI/REI for exact recipes.
Neptunium Rod
One of the best uses of Neptunium is crafting a 
Neptunium Fishing Rod. This rod has the best fishing stats in the mod — faster bites, better loot, and higher durability. It can be enchanted with vanilla fishing enchantments like Luck of the Sea and Lure.
Tips
- Fish in large water bodies with a Neptunium or diamond rod for best Neptunium drop rates.
- Use bait and hooks to speed up catches.
- Neptunium armor gives water-related bonuses — useful for underwater exploration.
- Store Neptunium in a
Tackle Box or chest to avoid losing it.