Schistura mahnerti

[Steve]

Hi, I rarely post in here although I've been a member for a while, but I have an oddity with one of my Schistura mahnerti which I wondered whether anyone might have any ideas about.

I have four in a 58G tank, and have had them for what's coming up to two years this March. They regularly change 'shade' depending on mood, ranging from very pale (usually after being disturbed by a water change) to fairly dark, sometimes almost black.
When they do this, the change is all over. However, for the first time one of them has now changed colour on only one part of the body: the uppermost (from the head down, about 1/3 of the length of the fish). This part of the fish is dark, and the remaining 2/3 is pale.

Does anyone know what might be causing this? Is it normal, or should I be worried?
I should note that this fish has partnered up, apparently, with my female (I know she's female from the huge belly...hehe). He had been chasing and spiralling with her for a while, recently, and the two now stick together at one end of the tank. Could this colour change be related to this or is it likely to be something else?

Tank params are fine, before anyone asks.

Thanks in advance for your ideas!

[Mark in Vancouver]

I would just keep a close eye on him to make sure it's not a permanent thing. Have you got sufficient water flow in the tank? Without photos or tank parameter details, there's not a lot we can say, I think.

[Graeme Robson]

I must admit, i've never seen this partial colour change before and this is after 8 yrs of me keeping many Schistura's. Settled Schistura's will show darken colours on them but this colour change only around the head is interesting. One possible factor may be the War paint pattern that some loaches like the hillstream loaches do when in breeding condition. Do you have any pictures?

[Steve]

Without photos or tank parameter details, there's not a lot we can say, I think.

Photo below. As I said before, tank params are fine (sometimes I take offence at being being asked this for the amount of time I've kept fish...checking params is the first thing anyone in their right mind does when something is out of the ordinary, although I understand you must deal with a lot of people who put fish like loaches into uncycled tanks or have nitrites et al. off the scale, it does grate occasionally...I'll let you off this time though... ).



As I say, in the two years I've kept them I've not seen a partial change such as this, only a complete all over change (which they regularly do).

I should also note, I did recently remove a second filter (an internal one used only for mechanical filtration), leaving only the canister filter to create flow. There's not been any issues with the other three schistura though, only this one, whatever that may indicate. And the flow is still pretty good.

[Graeme Robson]

Certainly looks like a mood colour change. For what reason, i haven't a clue. Keep an eye out for little free food. You never know!

[Steve]

Certainly looks like a mood colour change. For what reason, i haven't a clue. Keep an eye out for little free food. You never know!

Ah, in that case I'll stop worrying: it's reassuring to have the eye of an expert look over my fish for me
He seems to have coloured up all over now too, so it was at least a temporary thing.