[Goatcheze]

I just noticed this 9 months after I started my 125g. I have 10 kuhli loaches in the tank and they usually are very shy, but whenever I turn the filter off, they always come out. There are only a few things I can think of that could be the cause.

1. The heater is in the sump, so water temperature goes down when the pump is off. Tank is usually 80F or 27C, but decreases to around 72F or 22C when the heater is off.

2. The sump causes a small vibration in the tank which they might not like

3. They might not like the high flow when the sump is on

I'm just really confused why this happens and I am wondering if I should move them to a new tank.

 

[jake21]

It is possible that the drop from 80 to 72 would have an effect as that is rather significant but I'm not sure - i would speculate it is vibration that is scare them. I have kuhli in three of my tank - 1 of them they hide 100% of the time 1 of them they have begun to hide less after 2 years - but i think the trigger was when i changed the substrate (why i do not know) and one well i have to push them away when i do water changes as they have no problem blocking my vacuum of the substrate. Why the difference in behavior i really can't say - I can't find anything common between the three tanks to explain the difference.

 

[SallImSayin]

I haven't experienced anything like that. Curious. I know mine behaved differently depending on the level the tank is at. I had them in a 29g on a stand and they were out and about. I moved them to a low tank (a few inches off the ground) and they hid all the time. I've recently moved them back to the 29g and they've back out during the day, again. I can usually see a few of them, at any given time, whereas the entire time in the low tank they hid. Who knows what could be bothering them in your tank.

 

[Griznatch]

Here's a thought... weather loaches are pretty sensitive to barometric changes and like lower water temps. I'm guessing to some degree other loaches would be too. I've never kept them, so I'm going off of cursory research. Could be turning off the sump drops that warm water current down enough to make them more comfortable. on the offchance there's some wacky weather front coming in maybe they are also being triggered by that?

 

[Plinkploop]

Here's a thought... weather loaches are pretty sensitive to barometric changes and like lower water temps. I'm guessing to some degree other loaches would be too. I've never kept them, so I'm going off of cursory research. Could be turning off the sump drops that warm water current down enough to make them more comfortable. on the offchance there's some wacky weather front coming in maybe they are also being triggered by that?

My horseheads used to go completely missing about 2 hours before a thunder or larger winter storms would roll in- I think you're on to something there.