Well if you are asking in this forum you will need to address humdity issues, aka venting.
Is your basement within 5 degrees if your tank temp year round? Then insulate now and save money later with less heating or cooling.
Also nsulation will end up lowering noise levels in adjacent areas
I am also asuming you are going to seal up, aka finish, the fish room, you reallyi dont want unprotected wood in a humid environment as you are asking for mold issues.