For anyone trying to get the AQ-40 pets that doesn't have frost damage (required to kill Viscidus), you can finish him off by carrying a spare weapon with a frost damage enchant, such as the newer elemental force.
I'm about half way done getting my old dungeon pets. I usually see 2-4 drop if I clear MC/BWL/AQ40 and Naxx.
I want my Mr. Bigglesworth!
Eumaeus, Guardian/Feral PvP Druid
GM - Lux ex Tenebris - Sargeras | Alliance
[6/6] MSV [6/6] HoF [3/4] ToES