I agree wholeheartedly with the explanations of what a mature aquarium is. However, I can tell you from first hand experience that I set my sidthimunki herd up in a brand new tank with brand new gravel and some old, some new plants, and an established filter and they are thriving! And when these buggars arrived stone cold due to heat pack failure and barely moving, and me sobbing hysterically, I hit the fish bag with a room heater at work (since I had to take delivery there) and once the water warmed up they were like a swarm of bees with activity and they haven't skipped a beat! And when I say cold water, I mean cold water!