Hi bro,
Your answer can be found here:
https://www.hdb.gov.sg/fi10/fi10218p.nsf/FI...AQ?OpenDocument
Excerpts:
Q5: Can I install any household item heavier than 150 kg/m2 (such as a safe exceeding 150 kg) in my flat?
A5: HDB flats are designed with an imposed load of 150 kg/m2. This is a requirement under the Building Control Act and Regulations for residential occupancy class.
It is safe for residents to place most general household items, such as furniture, appliances, television, washing machine, refrigerator, piano, fitness equipment, etc, including common standard-sized fish tank/s in their flat as these items are not concentrated in one location and their weight will not affect the uniformly maximum distributed load of 150 kg/m2.
However, if you intend to place unusually heavy items (such as safe exceeding 150 kg or a large-breeding aquarium-size fish tank) that exceed the allowable weight or size limit, you must get approval from HDB before installing these items. You will need to submit your application to the HDB Branch Office managing your flat, stating the size, type, weight and location of the fish tank (see sample copy) . Alternatively, you can submit your application using the email facility.
HTH