The trad brewpubs are likely to be packed to the gills with jolly Karneval people. If you want to eat a bite better head elsewhere, like the South African restaurant mentioned.

Some good eateries also tend to close down over the peak Karneval period as main demand is for Frikadelle and Currywurst. Downtown maybe the Friesenstrasse/Friesenplatz area would be a good place to find a bit wider choice.