v3.25.2
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2025
Aug. 05, 2025
Document Information [Line Items]    
Document Type 10-Q  
Current Fiscal Year End Date --12-31  
Entity Central Index Key 0002000046  
Document Fiscal Period Focus Q2  
Amendment Flag false  
Title of 12(b) Security Fidelity® Ethereum Fund Shares  
Trading Symbol FETH  
Security Exchange Name CboeBZX  
Document Period End Date Jun. 30, 2025  
Document Fiscal Year Focus 2025  
Document Quarterly Report true  
Document Transition Report false  
Securities Act File Number 001-42163  
Entity Registrant Name Fidelity® Ethereum Fund  
Entity Incorporation, State or Country Code DE  
Entity Address, Address Line One 245 Summer Street V13E  
Entity Address, City or Town Boston  
Entity Address, State or Province MA  
Entity Tax Identification Number 99-6342530  
Entity Address, Postal Zip Code 02210  
City Area Code 800  
Local Phone Number 343-3548  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   66,450,000