#1 The first issue being that the hardwood floors got refinished downstairs (which is why I have some unknowns as to what happened in my ranchu aquarium while I wasn't home), and although my bedroom upstairs where my fish reside were left with a closed bedroom door the dust from the downstairs floor still managed to seep into my room... hence wood dust getting into the aquarium. Not to mention the fumes throughout the house from the staining process and such may have also been a contributing factor.
#2 The power had apparently gone out at some point during this process... for how long exactly I am uncertain but I believe this may have contributed to problem #3.
#3 Filter failure which may have happened due to the power going out and it's honestly the first time this unit has failed in my tank. For goldfish, having water movement and constant filtration is basically a total must have since goldfish create a lot of waste, but wait... I have an air filter as well, which brings me to issue #4.
#4 Some where along the lines of doing regular tank maintenance (honestly this next part is a total mystery) but some how my air check valve was going in the wrong direction and hence no oxygen was actually going into the tank from the air pump (which explains the lack of bubbles being produced after I cleaned the decor).
#5 It could also be that once all the filtration had failed it caused the water parameters to drastically change, which in itself could have eliminated the ranchu. However I did perform a 50% water change before I left the fish to fend for themselves for 2 days (they did have an auto-feeder so food was not an issue, and there was uneaten food in this gravel-less setup when I did return), but it's a little hard to believe that even with the filter failure the fish didn't survive those short few days (I mean they did survive being shipped to my house in breathable bags for a few days).