300 Gallon Piraya Tank

So my sump and drip system was not ready yet and I couldn't look at the empty tank anymore so I used my external filter to get the tank going in the mean time. External filter only rated for a 150 gallon that's why tank is not full. Fish we're added about 2 hours ago so they are still adjusting. It looks too big for them now but soon they will fill it out.