Black Ghost Knife changes colour at night

[Daffodil]

Hi,

I have had my black ghost knife for about 6 months now and he seems to be doing well. However yesterday I noticed the strangest thing. When I turned the tank light on, a patch on his body was red instead of black. It did not look like a scrap or a cut. After about 2 minutes the patch had slowly changed back to black. I was a bit worried about him, as I have never heard of anything like this before so I got up in the middle of last night and turned the lights on. Sure enough half of one side was reddish and faded to black in a few minutes. Most of the time he swims around and seems healthy.

I haven't been ably to find anything about this on the net. I was wondering if anyone here knew anything about this, particularly if it is a sign that he may be unwell or if it was just one of the many quirks of the BGK.

Other information that might be useful - pH - 7.6, Ammonia - not detectable, Nitrite - not detectable, tank size - 30G, water change - 1/3 weekly, tank mates - bristle nose catfish, Angelfish


Any help would be greatly appreciated!

 

[NatakuTseng]

Without actually being able to see the fish, I would say that he is just changing colors depending upon the lighting. Many fish do this, cardinal tetras for example will get almost white in the dark, turn the lights back on though and in a few mins they will be back to the blue and red normal color. Its probably just that he is changing his body pigment depending on the lighting, especially if its just going away like you say it is.

 

[StreetCypher]

My RTBS also did that. When i turned the light on at night, he would be really pale. after a few minutes he regained his black body and red tail. I learned that fish use platelets to control their colors. They turn them "on" when needed (daytime) and turn the "off" when not needed (nighttime). Probably nothing to worry about, but keep an eye on him anyways.

 

[oscar83]

i had a bgk a few years back and he did the same thing since the day that i got him. he lived a happy and healthy life until he jumped out of the tank and my cat ate him... RIP.... but yeah, i think you have nothing to worry about.

 

[Daffodil]

Thanks guys,

I have now stopped worring. I was hoping it was just 'what they do'. He is still very lively and seems quite happy but I'll keep an eye on him anyway.