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Scared Fish - Iwagumi

Joined
6 Nov 2010
Messages
417
Location
Kings Hill, Kent
Hi All,

I have just rescaped my tank and compared to my past setups im pretty pleased with how it looks.

However, as you can see below I'm having issues with fish huddling in the front corner and they will not move until the second the lights go out.

I can understand that fish in the wild would act like this is they have no cover but I don't see anyone else with Iwagumi tank photos showing the fish huddled in a corner. The photos I see always show shoaling fish weaving the rocks.

Are my fish just adjusting or is this likely to be a short term setup for me?


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If your last tank was densely planted, they're probably not used to their new sparse home. I've experienced something similar before, but mine never really came around to the iwagumi; even when it did fill in. It sort of lead me to believe some fish just aren't suited to an iwagumi. My tank in question had a new neons in it and they really didn't do well when the lights were on. The moment the lights were off they would come out, but when they came on they'd hide (tried different fixtures, levels of light, etc). A few eventually got used to it, but the bulk were still rather shy after a few months. In the end I moved them to another nano with more dense planting and they were fine. They've been in there ever since and have done really well.
 
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I had problems with chili rasboras that were swimming frantically in one corner of the tank, despite the tank being fairly heavily planted.

I tried all sorts of things - reducing lighting, reducing filter flow, changing from a lily pipe to a spray bar, and even made some 'decoy' fish out of neoprene rubber and suspended them in the tank. I also dramatically increased the population of chilies, from 7 up to 19. The change to a spray bar helped a little bit, but nothing else did.

Then I gradually started allowing the hornwort in the tank to grow unchecked until the tank was fairly choked with a thicket of it. At last, the chilies calmed down and started swimming slowly and calmly in the middle of the tank. Removing the hornwort sent them straight back into panic mode. It was as if they were afraid of the open surface.

I allowed them a week or so of chilling out underneath the overgrown hornwort, now with the lights on 100% brightness to compensate for the reduced light on the carpet plants. The bright light didn't seem to matter, provided there was surface cover.

The good news is that after a week or so like this, I started gradually thinning out the hornwort, little by little. If I removed too much they would become slightly perturbed and sometimes I had to throw a bit of hornwort back in. I kept the spare hornwort in a bucket, and I'm now keeping it in a large vase on the windowsill in case I need it again.

Last night I removed pretty much the last few sprigs of hornwort, and now you can see what the tank is meant to look like. The chilies are still calm, despite the fact that there is now loads of open surface and the lights are fairly bright (running at 70% on the LED controller, giving about 1400 lumens over a 25 litre tank).

Not only are the chilies calm, but throughout this period of acclimatisation they have dramatically coloured-up. Previously they were very pale - almost colourless. But now they strut around showing off their smart red suits, and the males occasionally square up to each other. There are now 14 of them in the tank, so I think I lost 5, possibly to stress while they were so unhappy. But I've been able to count 14 for several weeks now, so I think the population is stable. They do slightly retreat into a corner whenever I do some major plant pruning, but it doesn't take long for them to come back out again if I temporarily turn the lights down.

So I do recommend getting hold of a large quantity of hornwort - enough to make a thicket over the whole tank surface, and let it grow until it forms a raft at least 2 or 3 inches deep from the surface. You could try other floaters, but perhaps the 'tangled' nature of the hornwort is important? The other advantage of hornwort is that it doesn't block the light completely. You'll be able to get rid of it gradually once your fish have chilled out for a week or so.
 
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I've seen some improvement after another day but that's generally after I've put food in. They eventually go back into their corner.

I'll try some floating plants which I'll gradually remove as you have suggested above. Hopefully that will help.

I have Cardinal Tetras, Ember Tetras and Golden WCMM's I find the cardinals to be the worst. When the Embers went in they shoaled brilliantly for days but then seemed to meet the Cardinals hidden away and maybe the fear caught on! I was hoping the bolder embers would entice the others out.

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I have the same problem with my Cardinal Tetras and Rummy Nose Tetras. My Celestial Pearl Danios are fine and seem perfectly at ease, playing happily amongst the hair grass and rocks. My Guppies seem pretty content too.
I might try some floating plants - I'm still at low lighting anyway battling the last of the stag horn so it might kill 2 birds with one stone.
 
Light substrate, bright light and zero cover all go to make for scared fish. They may come round after a while when the scape grows in but you may struggle to see any relaxed behaviour from them in that sort of set up.
 
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