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Which way do the fish prefer their caves facing wrt the current? Upstream, downstream, 45 degrees...?

In breeding Hypancistrus and Panaque, at 90 to 100 deg to the current on the floor. I run the current right to left along the middle of the top of the tank (moving surface) so it goes down the far side and back along the floor.

Jools

I'm sure glad you asked this question because its something I've always wondered, and people have often told me to just give a bunch of caves to give them a choice, but this isn't as economical.

I should add that in all cases, putting a flat piece of wood or slate over the caves has helped.

Jools

Just dived into the fishroom and took a video of a tank which probably shows it better? Available in HD.



Jools

I suspect Jools has nailed it, and that caves should be placed perpendicular to slightly downstream.

Perhaps a little bit of backstory: I placed a bunch of artificial caves in a stream to study sculpins, and noticed that caves oriented upstream tended to get clogged by leaves (one cave was actually completely filled with a neat 'pancake stack' of leaves), and those oriented downstream tended to have the entrance blocked by sediment. I did a literature search but couldn't find anything on fish preference wrt orientation of caves in streams.

EDIT: Damn nice setup, Jools. Do you have any thoughts on why the fish prefer caves covered by slate or wood? Just that the entrance is better hidden/shaded, or something to do with the water flow?

For what it is worth
I place all caves at all angels to the power heads I use 2 x caves to fish so 5 fish = 10 caves.
I cover the caves totally with slate, small stones and bogwood.
A litter of leaf and plant matter across the floor of the tank.
The fish find the cave they want and spawn.
It has worked for around 20 Sp of Hypan Pecs and B/n’s for me.

Mike_Noren wrote:I did a literature search but couldn't find anything on fish preference wrt orientation of caves in streams.

EDIT: Damn nice setup, Jools. Do you have any thoughts on why the fish prefer caves covered by slate or wood? Just that the entrance is better hidden/shaded, or something to do with the water flow?

Well sculpins aren't loricariids, but Nico et al. 2009 have some notes on Pterygoplichthys burrows in Florida. They apparently prefer one of the banks when the river bends.

LG Nico, HL Jelks, T Tuten (2009) Non-Native Suckermouth Armored Catfishes in Florida: Description of Nest Borrows and Burrow Colonies with Assessment of Shoreline Conditions. Google pulled up this link to a PDF: http://fl.biology.usgs.gov/pdf/ansrp-v09-1(LR).pdf

I'd suggest that the stronger the current a pleco lives in in nature, the more particular they are. I'd also suggest this preference erodes with captive populations. Many are found in standing water, so they're not fussy. Some of the fastest water plecos don't use caves as such but in-between is what I am aiming at.

Havard, for example, only used one or two caves in his many success and suggested that ensured the best male and female spawned. If you're dealing with several $200 fish, a few more caves don't appear a bad investment. However I often remove caves once I know what works.

I prefer to cover them with slate so I can just about see what is going on but the cover is about the females. Females will often get pretty beaten up in the spawning event (depending on genus) are pretty rough, by all accounts, so are , and . Anyway, you'll see in my video pleco burrito caves in the background, these are often where the females go to coalesce.

Meantime, the cover around the spawning cave allows a female or three to hang out near the males cave without being out in the open with I feel helps especially with first timers.

Jools