It is recommended to have 1 lbs per gallon for both rock and sand in the system. Without enough, fish are unable to establish territories and there will be increased aggression. You will end up seeing as the tang needs a large area and need to be in very large tanks, of upwards of 100 gallons.
In terms of lighting, a single taotronic LED
panel will cover it fully for the cheapest price I've seen on the market.