The nearest LRT is "Pudu" at the Ampang LRT line. It is about 10min walk from there.
From Time Square you can walk to Pudu market in about 15min.
The area around Jalan Pasar is also has many shops selling goldfishes and other aquarium fishes as well as aquarium equipment (water filters, lamps, food etc.)
Here is a great video showing the different cultures and people in Malaysia singing together at the Pudu wet market in Kuala Lumpur: