There is no national law prohibiting Sunday fishing for trout on Tweed, such as there is for salmon and sea trout. However, there is a Protection Order in place for the whole of the Tweed catchment, which makes it a criminal offence to fish for freshwater fish without permission (ie anything other than salmon/sea trout). If the Associations do not allow Sunday fishing, then any trout angler fishing would be in breach of the PO and leaving themselves liable to criminal proceedings.....I think there may be some very limited Sunday fishing allowed for trout, further down the system, though I cannot recall which club, and I am not 100% on that so cannot be sure.