Bucket of Tadpole
minecraft:tadpole_bucket
Made using a Bucket rather than crafted directly. Doesn't stack.
How to get it
No direct recipe — it's made using a Bucket:
Crafting 
→ 
Bucket
minecraft:tadpole_bucket
Made using a Bucket rather than crafted directly. Doesn't stack.
No direct recipe — it's made using a Bucket:
Bucket