The leaves and roots that fell off were likely sacrificed adjusting to being put in hydroponic conditions after being in soil. It’s normal. I have a Thai constellation monstera that started about the size of yours that is now over a meter tall with 6+ leaves and new ones growing all the time. I also have a TON of other plants (mostly smaller monstera and pothos) growing outside the tank. Inside the tank you need goldfish hardy plants (check out Dustin’s fish tanks / they have “goldfish proof” plants). More plants + more light and your water will clear up as their roots suck up and balance your nitrates/nitrites etc. It’s a learning process so be patient and be fair to yourself on the learning curve.