I have a 450 gallon Tote System and I live in San Antonio Texas and Since this cold snap I have been loosing fish,, I have been maintaining 60 to 70 degree water for  Mozambique tilapia ,, not sure if i need an anti-biotic or to Get the water Warmer. **I see the fins looked frayed when swimming **the scales look unhealthy not sure what to look for Using the API Test Kit my readings are Ph = 6.0 p…