Tunafish Trenches is the fifth stage in Quarantine Isles. This stage is a remake of Frozen Tuna Front.
A harder version of Frozen Tuna Front, where Master A. is replaced by Professor A. and all other enemies are boosted to 800% strength magnification except Metal Hippoe, which increased from 100% to 200%.
The stage doesn't give many options since Doge Dark, St.Pigge the 2nd and Professor A. are the only enemies with traits.
Lineup: 3-4 meatshields (one can be replaced with Thaumaturge Cat for safety) and units with long range (Paris Cat, King Dragon Cat, Prisoner, etc.). Use Ururun Cat/Awakened Bahamut Cat to deal with the traitless enemies.
For Professor A, you can use tanky units like Jamiera Cat/Manic Jamiera Cat (alt. Balrog Cat/Cats in the Cradle/etc.) when most of the peons/traitless enemies stopped/reduced spawning.
You can also stall by using Cyberpunk Cat or other units with enormous range, like Super Galaxy Cosmo or Aphrodite.