tank substrate for gouramis

Question
What is the substrate for my tank. I currently have a dwarf,gold,and blue gourami a serpae tetra, a marble angel and a chinese algae eater. I plan on introducing a school of 6-8 barbs also. I have black and white rock on the bottom now.

Answer
I'm not sure what size your tank is, and I'm sure you understand what the word substrate means.

Substrate is whatever is at the bottom of your aquarium, whether its gravel or sand or nothing. Anything is fine for gouramis, they aren't bottome feeders.

If you mean you are introducing a shool of tiger barbs, you are going to be in a lot of trouble. Tiger barbs are huge fin nippers, and they will rip your gourami and angel fish to shreds.