Gymnogeophagus Balzanii Question???

[neonvertigo]

I got a pair of these guys (4") about 6 months ago and at first the male looked really good. He had a great big head on him and nice color. He has since deflated and lost alot of color. The weird thing is the female looks better than she did when I got the pair.
I was feeding them lots of sinking carnivore diet but have recently introduced lionhead formula food to try and "re-inflate" his head.
The tank is at 55g at 78° with no detectable nitrate or ammonia... it gets a 25% change once a week.
Just trying to get an insight as to why this happened and what I can do to restore him to his former glory.
BEFORE

NOW

THE TANK

 

[Aquanero]

I know these guys need a chill down period of about 3-4 months to replacate winter. They should be kept at around 75-78 and then "winter" at about 60 degrees or so, without this cooling down time they will start to fade as may be the case with yours. Some of the guys that keep them may have more specific info but that's about the deal with them in a nutshell.

 

[darippa]

They usually lose the nuchal bump when their competition is taken away. They do best when kept in a small school. Temp has to be lower than average Geo tank.

 

[neonvertigo]

hmm maybe I'll look around for another few then and try to bring the temp down a bit. thanks for the feedback!

 

[abarilot]

Not exactly sure why there humps went down but both responses above sound logical. One of the main things to keep gymnos healthy is to maintain seasons and the easiest way (at least for me) is to keep them in unheated tanks. My gymnos range in temperature from high 70s to low 80s in the summer to low 60s in the winter. Good luck with your balzanii!

 

[peathenster]

I think it might be more of a seasonal thing. The Uruguayan group I received from Ken include at least two fully grown males, and both have lost the hump, so the lack of male competition alone cannot explain this.

Ken also brought back a pair in 2008 and they behaved similarly - the male lost his hump in a few weeks. However, Ken was able to breed them in 2009, at which point the male got his hump back. The fact that it took a year seems to suggest that they had to go through a whole cool-hot cycle...