The following rules, established by the Flen Fishing Conservation Area Association, apply to fishing in Lake Flen.
- All fishing without a valid fishing license is prohibited.
- Children up to and including 15 years of age fish freely without the requirement for a fishing license.
- Fishing licenses are only valid for sport fishing (no fixed gear may be used).
- The cards are also valid for the winter season and are valid for angler fishing and ice fishing (max. 10 anglers/card).
- Annual cards are valid for one year from the date of payment.
- Fishing licenses are personal and may not be transferred.
- It is permitted to bring your own boat.
- Trolling and drag fishing are permitted.
- Fishing license and identification must be presented upon request by a fishing supervisor.
- For pike perch, the minimum size is 40 cm, smaller fish will be returned.
- Crayfish fishing is not included in the fishing license.