what are you going to do with them once they grow??
I personally couldn't get the video to work so i don't know exactly what fish you have but with the silver sharks for example, they don't have enough tank length to grow into, these should be getting to 13" and be living for an excess of 10 years, this will not happen if they are kept in a 4foot tank
ammonia and nitrite are 0, nitrate is around 15ppm... not sure about hardness.
weekly water change, around 10%.