Kuhli loach substrate

CAPSLOCK

Elite Fish
Jul 19, 2004
3,682
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Cape Cod
#1
The results of my experiment are in: kuhli loaches prefer rocky gravel.

This was statistically significant. Rocky gravel was the most popular choice, followed by small gravel, with sand being used the least. Rocky was chosen almost twice as often as the other two substrates combined. Tank was set up with those three choices of substrates. They had a PVC pipe in all three choices, and one plastic plant, and were fed equally over all three substrates. This went against my hypothesis that they would prefer sand, and rocky would be the least liked.

Possible explanations: There weren't many hiding spots, so we think they liked the rocky gravel because they could hide better and could burrow under it. During the last few days of the experiment, two took to hiding under the pipe in the rocky gravel. None ever burrowed in the sand (although we did see them sifting through the sand occasionally. Next year, I plan to test this hypothesis again, using a well planted tank so everywhere is shady and they might not need to hide among the gravel.

This is good, because I have large to medium gravel in my tanks. Just thought you might like to know.
 

lordroad

Large Fish
Sep 2, 2004
989
7
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Shelby, NC
www.joshday.com
#3
Wow, what a myth buster! thanks caps.

I keep 5 kuhlis in my planted ten gallon, 3 regular, 2 black kuhlis. They can burrow in my 2 mm gravel when they get freaked or the mood takes them. My tank is also heavily planted.

One neat thing I've found with kuhlis and live plants, at least the feathery, whorly ones, is they come out at night and hang in the plants like snakes in trees. it's really neat to watch with a flashlight as they just kind of lie there. First time I saw it I thought one was dead.
 

CAPSLOCK

Elite Fish
Jul 19, 2004
3,682
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Cape Cod
#5
Yeah, everything I've heard from books and people here is that their kuhlis love to play in the sand. I hypothesized that sand would be preferred. I'm planning an experiment for next year to see if they still prefer rocky gravel if the tank is well planted (so they don't have to hide in the gravel, everywhere will seem hidden). I also want to try a finer sand (what I used was unused pool filter sand), or aquatic dirt or some such. I was really surprised they preferred the big gravel.

My kuhlis do that with fake plastic plants, as long as the leaves form a "shelf" for them to rest on. I thought one was dead at first, too.
 

radamsk1

Large Fish
Apr 23, 2005
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Long Island, NY
#6
*thumbsup2 I also have found this true in the past, as they often preferred a large substrate to sand. I actually once had a few of them in a community tank and read up on and found that sand is best. I replaced the gravel with sand and they didn't seem to like it! How odd that was, and all they did then was hide in their rocky cave I build. I switched back to the gravel and they appeared much more happy. However, i believe they can conform to either substrate, as long as adequate hiding places where they can dig around are provided.
 

NoDeltaH2O

Superstar Fish
Feb 17, 2005
1,873
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SC
#8
Thanks a million CAPSLOCK. The fish community only gets better when people like you experiment with fish. I've been meaning to do some experimentation myself but just didn't commit the time to it. Keep up the good work, it will make all of our kuhlis happier.
 

CAPSLOCK

Elite Fish
Jul 19, 2004
3,682
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Cape Cod
#9
I was really surprised no one else seemed to actually have done the experiment before. It is written in all sorts of aquarium books, but no one's ever really tested it... they just assume. Even all the data I found was seeing where loaches (not kuhli loaches) liked to stay in their natural setting... observational stuff in the field.
 

Apr 27, 2017
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#10
Hi all. I have a Juwel Trigon 190 with 3 Kuhli Loaches. I recently replaced my substrate to a large rocky substrate. Probably 0.5-1 cm rocks. Opinions on if this is ok or not?