There isn't any closed season in Scotland on rivers, in fact there is no licence system as there is in England and Wales but there are
rules.
If you can find the necessary information on the web there is some really good fishing on the rivers but you need permission to fish. There is a tackle shop in Glasgow that might help you with this.
Coarse fishing in Scotland is much wider spread than it used to be and some of the reports I have read make it a very worthwhile prospect whilst on holiday. Good roach fishing, excellent pike fishing, and some of the Scottish rivers are purported to hold enormous chub in abundance.