Greetings all! I have set up a 4 by 2 by 2 feet tank which i guess is a 100 gallon tank in terms of water capacity. I have placed a few plants and 4 flourescent tubes 2 of 6500 kelvin and 1 each of 4000 and 8000. It has been 3 days now and there are no fish. I wish to use either the Black widow or the Serpae tetra to cycle the tank may be after about 10 days. I am thinking of adding about 6 or 8 of either. Please suggest which species would be better?