so any way i have some bullseye snakeheads i cought from my lake, i kept some in the lake water that i change out daily, and i put some in the tank, i made sure the ph levels were good but the ones in the lake water seem to be much much healthier, the ones in the tank are darker and less active, the ones in the lake water are very active and more brighlty colored, what are some things that could be difrent what should i have in my tank to keep my snake heads healthy