My fish haul is at 18. Three are RTR and a further six are built + painted Parkside kits simply needing 1950s-era numbering and some weathering powders. The other nine are kits to be built; I have that as my 2025 mission!
Rapido's ex-GNR insul van hopefully arrives this year. Just a BR 20t brake van still to be bought; then my rake of 20 is ready. 
My two LMS dia.1663 Cambrian kits will be added to a general merchandise fitted freight instead.
My intended train comprises 12' and 10' wb vans + conflats. I had planned to include 2 examples of LMS dia 1663, a 9' wb design van; but it would be unlikely on a fish train, due to the 35mph operating speed limit imposed in the 1950s.
9' wb wagons were limited to a max speed of 35mph (versus 45mph for 10' wb). The restrictions were imposed following several derailments of short wheelbase wagons, due to them "hunting" (laterally oscillating) along sub standard track, until the flange rode over the rail-top.
In the early years of the Big Four, 9' wb fish vans were built by the LMS (dia 1885) and LNER (dia 23). By the late 1950s, the 9'wb fish vans were relegated to non-fish use, e.g. for general merchandise.