Water may be yellowish, Fish dart and gasp, Live bearers do poorly. Acid from fish, waste or decaying food. Right if tank is filled with new water. Start Right neutralizes chlorine, heavy metals, and harmful gases immediately. Stimulates natural slime coat on fish.
Lights are to bright or alkaline water.
Keep ph at 7.0 or lower. Water is Hard . Use Aqualizer or Natural Colors and Jungle Water Softener. Jungle Water Softener discourages green slime and eliminates white water line. Half inch thread-like worm hanging from fish.