Sick Neon Rainbowfish?

[ShyGecko]

I have 3 neon rainbowfish, 2 male and one female, and I think my female is sick. My two males are very bright blue with extremely red fins, and my female used to be the same with bright yellow fins, but lately she has turned from a brilliant neon blue, to a dark grey/blue color, and her fins have gotten this sickly green hue to them. The rest of the fish in my tank are all very healthy and showing full color, but she isn't. She's been like this for a while, 2 or 3 weeks, and about a week ago she started acting like she was going to die so I threw her in my 10 gallon tank that doesn't have any other fish in it, to see what she would do. If she is sick I didn't want her to die and one of the other fish eat her and get sick also. She didn't like it at first, but after a couple hours she started moving around a little more, and started eating better when I fed her. Her bright colors started to come back, and after a few days she looked pretty much good as new, and she looked rather lonely, so I put her back in to her original tank. Now she is right back to looking like she did before I moved her. Could she just not like the tank I have her in, or is something in there making only her sick?? I don't know what to think of her. LOL Any suggestions?

 

[azn dreamer]

Has the original tank cycled yet? Whats the reading for ammonia, nitrite, and nitrate?

 

[Allivymar]

How strange. I would def check water parameters just in case, although why one fish and not the others of the same breed (unless maybe its immune system is lowered?). I don't know much (anything LOL) about rainbowfish, but maybe it some sort of breeding change? Or maybe it's being picked on by the others?

 

[TheNewGuy]

I would also try taking the males out of the large tank and then put the female in the large tank with out the males to see what happens it maybe a mating thing.