It has a Hard Outer Layer, The Fish Scales are attached naturally to the fish skin which is cured, then the scales are individually (or sometimes for cruder versions, as a whole) laquered with Murker Blood called Lacker, hence the name.
As a Scale mail, its more effective against Piercing and Blunt attacks than chain, but is less flexible for manuevers, But as a Natural product far more flexible than metal scale mail.
Scale Armours are considered half-flexible, half-rigid for armour proficiency rules. No penalty is given if you only have one armour skill, just the Initiative reduction is reduced.
In Breylake its common enough to aquire (+50%), Beltayn and either Jesemby Bridgetown or Jesemby Forttown it can be found fairly well(+25%), but due to its poor durability, items found in other cities are more likely to be second hand (+50% avail, -35% HP) or poorly stored (-5% HP)
Hard Lackered Fish Scale Armour
Hauberk 75% 45% 25%, I: 5 (15), AF: 7, DR: -1, HP 100[30%]
Shirt 85% 55% 35%, I: 5 (10), AF: 7, DR: -1, HP 70[30%]