Sick Brackish Tank

[gordonjosh]

So, I recently (within the past month) started a 120 gallon brackish tank. I have been slowly raising the salinity to try to get it around 1.008-1.010. There are 2 silver scats each about 2 inches long and 5 archerfish around 1.5 inches long. The scats couldn't be happier and gobble up food like pigs. The archerfish eat as well but they (except for one) have developed discoloration on the bottom of their bodies, their bodies on the rear and undersides have all turned a dark color like a gray or black and two of them are losing their black stripes (they are turning to a silverish color.) They all appear to be healthy and even picked off a couple of crickets from the hanging ivy above the tank, but this coloring is obviously not normal and I don't want to lose the fish that I specifically set this tank up for

 

[gordonjosh]

I assume the water quality to be very good as part of my salinity increasing involves changing out about 5-10 gallons of water every 2 or 3 days. And the tank was started with gravel from another tank and cycle to give the bacteria a jump start

 

[CFC]

The black patch normally shows when the fish are fighting for dominance, i take it your fish are all new and a hierarchy has not been established between them? Once they have sorted out their positions in the group and which fish is the alpha they should revert back to normal colouring with just the lead fish showing the dark patch when it is putting the others in their place

 

[Discomafia]

Wow, that's really interesting to know. I'm sure this occurs with other fish too...