Freshwater fish turning yellow?

Lindsey

Hello!
We have a recently established freshwater tank (30 gal) with biowheel filter, aerator, etc. We cycled the tank for about a week before adding fish, and it used to house goldfish with its previous owner and was never quite dried out before we replaced the water and cycled it to start our tank.

We don't have anything overly complicated in there (two mollies, a few neons, tiger barbs, and a couple of zebra danios). The problem is that one zebra danio has began to turn yellow where they all used to be white. I've done a little googling of danios and apparently it's normal for them to have yellowish coloring--but I am worried because the rest of them don't seem to be having the same issue. Also, we have a white molly with big fins, and the tips of it's fins seem to be yellowing as well. I am wondering if this is something i need to worry about and if so how to rectify the situation. Thanks for any help you can give.

-Lindsey[/code]

Falina

What are your water parameters Lindsey? You should get a liquid test kit if you can and test for amonia, nitrite and nitrate. What did you use to cycle the tank? It seems unlikely that a tank would cycle in a week. 4-6 weeks is more common. It seems to me that your tank is still cycling which may be why the fish sem discoloured.

Lindsey

I actually tested the amonia, nitrite, and Ph today with liquid kits and all came up normal. I am not sure about the nitrate. thanks for the insight about the cycling, I hope that the fish end up doing okay!

fish_4_all

It could be an adaptation to the color of your substrate. What color is it? Other than that I have never heard of yellowing in a fish like that except for normal coloration.