The Derry river rises north of Tinahely and flows through Shillelagh before entering the Slaney at Killdavin. It is primarily regarded as a spawning river for the Slaney. The Derry River holds small brown trout averaging 6 ounces. The river is very overgrown and is rarely fished except by a few local anglers.
The Derreen River rises north of Hacketstown in Co.Carlow and flows southwest to meet the Slaney below Tullow. The river holds occasional salmon in the spring. upstream is better known as a trout river,the average size of the trout is around 0.5lbs and it can produce a very occasional fish to 3lbs.
The best of the fishing is from March to June.
There are two angling clubs with fishing rights on the Derreen River and the remainder is in private hands.
Bye-law 897 of 2012 prohibits the use of any fish hooks, other than single barbless hooks, and the use of worms as bait in angling for all species of fish in the waters specified and revokes both Angling Bye-law No. 888, 2011 and Eastern Fisheries Region (Angling) Bye-law No. 824, 2007. The list of waters this bye law applies to is available at the following link: ANGLING BYE-LAW NO. 897, 2012 [.pdf, 19 KB]